Given the task definition and input, reply with output. In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: pooja travels from a to b a distance of 800 miles in 10 hours . he returns to a in 5 hours . find his average speed ?
Options: a ) 123.07 mph , b ) 100 mph , c ) 150.07 mph , d ) 200 mph , e ) 300 mph
a