A biased coin with probability p, 0 < p < 1, of heads is tossed until a head appears for the first time. If the probability that the number of tosses required is even is \(\frac{2}{5}\) , then p =
1
\(\frac{1}{2}\)
2
\(\frac{1}{3}\)
3
\(\frac{1}{4}\)
4
None of these