If a certain coin is flipped, the probability that the coin will land heads is 1/2. If the coin is flipped 6 times, what is the probability that it will land heads up on the first 4 flips but not on the last 2 flips?  Choose one.
A) 1 / 8  B) 1 / 16  C) 1 / 32  D) 1 / 64  E) 1 / 128

Rationale: "p ( hhhhtt ) = 1 / 2 * 1 / 2 * 1 / 2 * 1 / 2 * 1 / 2 * 1 / 2 = 1 / 64 the answer is d ."
Answer: D