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.

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.

b. a lightning bug, plug of grass, and a worm