Solution:(c) There are three cars parked outside: a Mercedes, a Jaguar and a Fiat. (Correct)(a) There are three cars parked outside: a Mercedes, an Jaguar and an Fiat. (Incorrect Article)
(b) There are three cars parked outside: an Mercedes, a Jaguar and a Fiat.(Incorrect Article)
(d) There are three cars parked outside: a Mercedes, an Jaguar and a Fiat. (Incorrect Article)