Respuesta :

ChoiSungHyun

Step-by-step explanation:

The trains are going in opposite directions.

For every 1 hour,

The trains are 75 + 63 = 138 miles further apart.

Number of hours to be 621 miles apart

= 621/138 = 4.5 hours.

4.5 hours after 1 p.m. => 5:30 p.m. (B)