Basic Mendelian Genetic Probability Question regarding Cystic Fibrosis

The question is:

"Cystic fibrosis (CF) is inherited as an autosomal recessive trait. Two carriers (heterozygotes) mate.

A) What is the probability that their first child will have CF?
B) Their first chiild is born and does have CF. The woman gets pregnant a second time. What is the probability that this second child will have the disease?"

For (A), I believe the answer is 1/4. What am unsure about is (B). Am I supposed to use the multitplication rule and write (1/4)x(1/4) = 1/16. Or, is the answer still 1/4?

I'm unsure. Please help thanks.