A scientist is using potassium-40, which is a radioactive isotope of potassium, to find the absolute age of a fossil by radiometric dating. The scientist determines that about three-fourths of the original potassium-40 atoms in the fossil now remain in the fossil. What additional information is necessary for the scientist to determine the absolute age of the fossil?
A. the half-life of potassium-40
B. the identity of an index fossil
C. the atomic mass of potassium-40
D. the total mass of the fossil

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

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the answer is c

explanation:

the glands which are associated with each description is given below: