Biology

The aorta is the main artery that carries oxygenated blood from the heart to the rest of the body, making it a part of the circulatory system. It is not related to the skeleton or skull.

Physiology is the branch of biology that deals with the functions and activities of living organisms and their parts, making option B the correct answer.

Bananas are well-known for being rich in potassium, which is an essential mineral for heart and muscle function. Among the options given, banana is the best source of potassium.

Histology is the branch of biology that studies the microscopic structure of tissues. It focuses on how cells are organized into tissues and how these tissues function.

Vitamin D is primarily needed for the proper absorption of calcium, which is essential for maintaining healthy bones. While it also supports immune function, the key and most direct role is in calcium absorption and bone health, making option C the most accurate answer.

According to authoritative sources including Wikipedia's 'List of mammals of Pakistan', there are approximately 177 mammal species reported in Pakistan. Other sources on wildlife of Pakistan mention around 195 mammal species. The figure 174 is the closest and most widely accepted among the given options, making option A the correct answer.

The human adult skeleton typically consists of 206 bones, which include both small and large bones. This is the standard number accepted in human anatomy.

Vitamin B12 is naturally found in animal-based foods such as fish and meat, so both options A and B are correct, making option C the best choice.

Humans have a total of 46 chromosomes in each somatic cell, including one pair of sex chromosomes (X and Y) that determine the biological sex of the individual.

The liver is the largest gland in the human body because it performs numerous vital functions including detoxification, protein synthesis, and production of biochemicals necessary for digestion. Other options like the pancreas and sweat glands are glands but are smaller in size compared to the liver.