Me gusta porque me ahorra dinero.

a) el auto
b) el taxi
c) el tren
d) el metro
e) la bicicleta

E) la bicicleta, because when you ride a bicycle nobody asks you for money, the car cannot be because you have to pay for gas for the car, on the train it may be another option, but you have to pay a ticket to go on the train, in the taxi the taxi driver asks you for money, in the subway you can have a pass card but you also have to pay for that card, the bicycle is the best answer

The answer is a but you could also use c if you want