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# Explanation

### Explanatory Answer

Given, the two metros depart at the time interval of 4 minutes.

Also the metro pass by Piyush at the interval of 12 minutes.

Thus the relative distance travelled by the metro in 12 minutes is the distance travelled by the metro in 4 minutes.

- 4 * (speed of metro) = 12 * (speed of metro – speed of Piyush)

Given, speed of Piyush = 70 Km/hr.

- Speed of Metro = 105 Km/hr.

Hence, option a. is correct.