What is the rhyme scheme of the second quatrain? in sonnet 100

the rhyme scheme of the whole poem is ABAB CDCD EFEF GG. the second quatrain of sonnet 100:

Return, forgetful Muse, and straight redeem

In gentle numbers time so idly spent;

Sing to the ear that doth thy lays esteem

And gives thy pen both skill and argument.

^ this is CDCD. the first line of this quatrain, c, rhymes with the third line. so the third line is also c. the second line of it is called d, it rhymes with the fourth line so it's also d!