Combine these sentences by turning one of them into a phrase.
icy winds make the continent seem even colder. they blow across antarctica throughout the year.
(a) icy winds make the continent seem even colder, they blow across antarctica throughout the year.
(b)icy winds make the continent seem even colder and they blow across antarctica throughout the year.
(c)icy winds make the continent seem even colder; and they blow across antarctica throughout the year.
(d)icy winds, which blow across antarctica throughout the year, make the continent seem even colder.

The right way to combine the sentences by turning them into a phrase is the following one:

(D)Icy winds, which blow across Antarctica throughout the year, make the continent seem even colder.

Explanation:

If we want a phrase, all we need is a subject and a predicate. Therefore, by adding the relative pronoun "which" referring to the icy winds we form a more concise phrase with a subject (Icy winds,...) and a predicate (...which blow across Antarctica throughout the year, make the continent seem even colder).  It is clear that all that appears after the subject refers to it and its acts, that is, it is said in the phrase that icy winds do two things:

1- they blow across Antarctica throughout the year.

2- they make the continent (Antarctica) seem even colder.