Total number of cases \(=2^{n}\) Number of cases when head comes odd numbers of times \(={ }^{n} C_{1}+{ }^{n} C_{3}+{ }^{n} C_{5}+\ldots=2^{n-1}\) \[\] Required probability \(=\frac{2^{n-1}}{2^{n}}=\frac{1}{2}\). \[\] Choice (a)\[\]