n = 10
Using Binomial expansion,
probability of getting success(head) = 0.4
probability of getting failure(tail) = 1-0.4 = 0.6
probability of getting at least one head P(x >=1) = 1 – P(x=0) = 1 – $\binom{10}{0}(0.4)^{0}(0.6)^{10-0}$ = 1 – $(0.6)^{10}$
Answer C