Tritium has a half life of 12.5 years against beta decay. What fraction of a sample of pure tritium disintegrates in 25 years?

$\frac{1}{4}$ $\frac{2}{3}$ $\frac{3}{4}$ $\frac{1}{3}$

$\frac{3}{4}$

The correct answer is Option (3) → $\frac{3}{4}$