Sunspots are dark regions that appear on the surface of the Sun due to intense magnetic activity that lowers the surface temperature in those areas. The first recorded telescopic observation of sunspots is credited to Thomas Harriot, an English astronomer, in 1610. He used an early telescope to observe the Sun and documented these spots before Galileo’s more widely known observations. This discovery challenged the long-standing Aristotelian belief that celestial bodies were perfect and unchanging. The presence of spots on the Sun suggested that it was dynamic and imperfect. Later astronomers such as Galileo Galilei and Christoph Scheiner studied sunspots more extensively and tracked their movement, which helped establish that the Sun rotates on its axis. Albert Einstein is known for the theory of relativity, Isaac Newton for gravity and laws of motion, and René Descartes for contributions to philosophy and mathematics. None of them observed sunspots first. Thus, Thomas Harriot is considered the earliest observer, making option D correct. His work contributed significantly to the development of modern astronomy and our understanding of solar activity.

The Paris Climate Conference, officially known as COP21, was held in 2015 in Paris, France. It brought together representatives from nearly every country to address the growing threat of climate change. The conference resulted in the historic Paris Agreement, a global pact aimed at limiting the rise in average global temperatures to well below 2°C above pre-industrial levels, with efforts to restrict it to 1.5°C. This agreement is significant because it marked the first time that both developed and developing nations committed to reducing greenhouse gas emissions. Countries pledged to set nationally determined contributions (NDCs), which outline their climate action plans. The agreement also includes mechanisms for monitoring progress and providing financial support to developing nations. The other options are incorrect because the Paris Agreement was specifically finalized in 2015. The year 2016 is associated with the agreement entering into force, not its negotiation. Understanding the timeline of global environmental agreements is important in competitive exams and helps in building awareness of international cooperation. Therefore, 2015 is the correct answer as it represents a milestone in climate diplomacy and global environmental governance.

Pakistan’s population constitutes approximately 2.65% of the world’s total population according to recent UN estimates. This makes Pakistan one of the most populous countries globally. Population statistics are important for planning economic development, resource allocation, and policy-making. A large population also presents both opportunities and challenges, including workforce potential and pressure on resources. Thus, 2.65% is the correct answer based on recent demographic data.

Hepatitis is a disease that directly affects the liver, causing inflammation. It is usually viral and leads to symptoms like jaundice and fatigue. Other options affect different systems, not specifically the liver.

Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are primarily composed of proteins, which are made up of amino acids folded into specific three-dimensional structures. This structure is crucial because it determines the enzyme’s active site, where substrates bind and reactions occur. Enzymes are highly specific, meaning each enzyme typically catalyzes a particular reaction. Vitamins and minerals may act as cofactors or coenzymes, assisting enzyme function, but they are not the main structural components. Carbohydrates do not form enzymes. Thus, proteins are the correct answer. This concept is fundamental in biochemistry and helps explain how metabolic processes occur efficiently in living organisms.