Events A and B are independent, with P(A) = 0.3 and P(B) = 0.6. What is P(A and B)?

For independent events, the probability that both happen is the product: $P(A\text{ and }B)=P(A)\cdot P(B)=0.3\cdot0.6=0.18$, choice A. Choice B ($0.9$) adds the probabilities, which does not give the chance of both events happening; it can even exceed the larger probability. Choice C ($0.3$) is just $P(A)$. Choice D ($0.5$) matches no rule for independent events. The probability of both events occurring can never be larger than either single probability, and $0.18$ is smaller than both $0.3$ and $0.6$.