Kit made contributions to a Roth IRA over the course of 30 working years. His contributions averaged $4,000 annually. Kit was in the 24% tax bracket during his working years. The average annual rate of return on the account was 6%. Upon retirement, Kit stopped working and making Roth IRA contributions. Instead, he started living on withdrawals from the retirement account. At this point, Kit dropped into the 15% tax bracket. Factoring in taxes, what is the effective value of Kit's Roth IRA at retirement? Assume annual compounding.

Answer choices:

A. $287,432.74

B. $305,432.74

C. $240,336.88

D. $298,232.74