. In a replicating DNA molecule, the region in which parental strands are separating and new strands are being synthesized is called a(n)

replication fork

Explanation:

The deoxyribonucleic acid (DNA) is a double-stranded helix composed of two long chains of nucleotides. The replication fork is a Y-shaped structure by which both DNA strands are separated in order to be replicated during cell division. In a cell, DNA replication starts at specific sites in the genome referred to as 'origins of replication'. A replication fork is generated by helicase enzymes that unwind and separate the DNA double helix strands by interrupting hydrogen bonds that hold the two DNA strands together. These DNA strands act as templates for the leading and lagging DNA strands. During DNA replication, the leading strand is synthesized continuously in the same direction as the replication fork, while the lagging DNA strand is synthesized in a direction away from the replication fork, in small pieces of DNA called Okazaki fragments.

i am positive it is c. condensing but i may be wrong

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.