Which of the following types of information are needed to construct a karyotype? I. Size of the chromosomes
II. Gene mutations
III. Age of the individual

#1
I and II only

#2
I, II and III

#3
II only

#4
I only

I only

Explanation:

To make a good karyotype all one needs is a photograph of the condensed chromosomes visible during metaphase of mitosis. The chromosomes are ranked according to size. It is not necessary to know the mutations or the age of the individual.

the answer to your question is:

c. complementary base-pairing