The half-life period of a first order reaction is 15 minutes. The amount of substance left after one hour will be :

Question

(a) $\;\large\frac{1}{4}\;$ of the original amount(b) $\;\large\frac{1}{8}\;$ of the original amount(c) $\;\large\frac{1}{16}\;$ of the original amount(d) $\;\large\frac{1}{32}\;$ of the original amount