A Mechanic Requires 3

A mechanic requires 3.5 h to repair a transmission, whereas an apprentice requires 10.5 h to make the same repairs. The mechanic worked alone for 1.75 h and then stopped. How long will it take the apprentice, working alone, to complete the repairs?

A) 6.25 h
B) 7.25 h
C) 7 h
D) 5.25 h
E) 4.25 h