Explanation:

- Two trains are moving in the same direction.

- Faster train speed = 44 km/h; Slower train speed = 32 km/h.

- Relative speed = 44 km/h - 32 km/h = 12 km/h.

- Convert relative speed to m/s: 12 km/h = $12\times \frac{1000}{3600}=\frac{10}{3}$ m/s.

- Time taken to pass = 72 seconds.

- Distance covered (combined length of both trains) = speed × time = $\frac{10}{3}\times 72$ m = 240 m.

- Both trains have the same length, so each train is 240/2 = 120 m.

- Option Analysis:

- Option 1: 135 m - Incorrect.

- Option 2: 120 m - Correct.

- Option 3: 100 m - Incorrect.

- Option 4: 75 m - Incorrect.

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