Q.12.  A fair coin is tossed 9 times the probability that at least 5 consecutive heads occurs is
(A) $\frac{5}{64}$
(B) $\frac{3}{32}$
(C) ${}^{9}C_5{\left(\frac{1}{2}\right)}^n$
(D) $\frac{5}{2^9}$