It really depends on which part of the sentence is underlined.
Subordinate clauses cannot stand on their own because they feel incomplete - thus, they have to be located within a larger sentence. Here, the subordinate clause is that can haul people and cargo.
On the other hand, independent clauses are complete on their own and do not need to be located within larger sentences because they are those larger sentences. Here, the independent clause is A pickup truck is the ideal vehicle.