(2) Car A 2, Car B 3.

③ Car A, car B 1.

Rent a car =300- 100=200 yuan.

① 300×1+200× 5 =1300 yuan.

②300×2+200×3= 1200 yuan.

③ 300× 3+200×1=1100 yuan.

So the third option is the most reasonable.