A fair 2 sided coin is flipped 3 times. What is the probability that tails will be the result at least twice, but not more than 3 times?  Select the correct option:  A) 5 / 8  B) 3 / 4  C) 3 / 8  D) 7 / 4  E) 5 / 6

Rationale: "at least twice , but not more than 3 timesmeans exactly 2 times , 3 times the probability of getting exactly k results out of n flips is nck / 2 ^ n 3 c 2 / 2 ^ 3 = 3 / 8 option : c"
Answer: C