JEE Math Practice Question

Let A, B and C be three events such that the probability that exactly one of A and B occurs is (1 $$-$$ k), the probability that exactly one of B and C occurs is (1 $$-$$ 2k), the probability that exactly one of C and A occurs is (1 $$-$$ k) and the probability of all A, B and C occur simultaneously is k2, where 0 < k < 1. Then the probability that at least one of A, B and C occur is :

1. A.greater than $${1 \over 8}$$ but less than $${1 \over 4}$$
2. B.greater than $${1 \over 2}$$
3. C.greater than $${1 \over 4}$$ but less than $${1 \over 2}$$
4. D.exactly equal to $${1 \over 2}$$