The middle of a chromosome where the two
identical segments from replication are attached
is called the

centromere

Explanation:

During cell division, the identical copies (called a "sister chromatid pair") are joined at the region called the centromere  Once the paired sister chromatids have separated from one another (in the anaphase of mitosis) each is known as a daughter chromosome.

this process is called "phosphorylation." a phosphate bond joins adenosine diphosphate to form adenosine triphosphate.

it has one origin of replication, but it proceeds in two directions - d)