Pairing of homologous chromosomes at metaphase of meiosis i appears to be critical for proper alignment, crossing over, and subsequent separation. this pairing is facilitated by sharing of sequence homology. if x and y chromosomes are so different, how can they achieve the necessary pairing?

The correct answer for the question that is being presented above is this one: "d. A special function of the spindle apparatus forces X and Y together."

Here are the following choices:
a. They do share short homologies at their respective tips.
b. They use a unique sex-linked mechanism not present in other pairs.
c. They do not need to pair because they are not a homologous pair.
d. A special function of the spindle apparatus forces X and Y together.