Answer:
D) Of the 4 people who have a sister, 1 of them also has a brother.
Step-by-step explanation:
P(B/A) indicates the probability of event B when event A has alredy occured.
Event A = The person has a sister.
Event B = The person has a brother.
So now P(B/A) means the probability of the person having sister who already have brother.
Hence choice "D) Of the 4 people who have a sister, 1 of them also has a brother." is correct.
