Correct Answer - Option 2 :

9 seconds
**Given:**

Speed of train = 96kmph = 96 × 5 / 18 = 80 / 3 m / s

**Calculation:**

Let the speed of the train be A m / s.

Let the length of the train be K m.

⇒ (K + 100) / 12 = 80 / 3

⇒ K = 220m

Then,

⇒ (100 + 2) / A = 51

⇒ A = 2 m / s

Relative speed = 80 / 3 – 2 = 74 / 3 m / s

Required time = (220 + 2) / (74 / 3)

= 9 seconds