The second quatrain of Shakespeare's Sonnet 100 is:
Return, forgetful Muse, and straight redeem (b)
In gentle numbers time so idly spent; (a)
Sing to the ear that doth thy lays esteem (b)
And gives thy pen both skill and argument. (a)
So, the rhyme scheme of the second quatrain is abba. However, this option is not included in the choices given. There might be a mistake in the question as none of the given options match the observed rhyme scheme.