The molecular clock is based on the assumption that:.
a) genetic mutations accumulate at a constant rate.
b) living organisms have equal amounts of carbon and carbon-14 in their tissues.
c) heating an irradiated substance releases trapped electrons together with a quantity of light directly in proportion to their number.
d) the products of uranium decay tend to solidify, separate out of water, and mix with salts that collect on the bottom of a lake or sea.

a) genetic mutations accumulate at a constant rate

Explanation:

The notion of molecular clock was first given by Linus Pauling in 1962. From the study of fossil , he found that number of amino acid in hemoglobin in different lineage changes almost regularly with time . So he concluded that rate of evolutionary change was approximately constant over time . This is known as molecular clock.

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees. 

nah.   i'm just sleepy.