What will be the time by light to travel 2 cm thickness of glass of refractive index 1.5?

$2×10^{-10} s$ $2.5 × 10^{-10} s$ $2.25×10^{10} s$ $10^{10} s$

$10^{10} s$

The correct answer is Option (4) → $10^{10} s$