Which edit to this sentence is necessary to correct a writing error?

Although the development of the interstate highway system made it easy to transport goods by truck, shipping companies never stoped using the train system as well.

A.
Change "stoped" to "stopped"

B.
Change "companies" to "Companies"

C.
Change "Although the" to "Although, the"

D.
Change "made" to "is making"


Answer :

I think A because if it’s talking about stopped using trains it’s a difference then stoped which is a series of steps or layers in the ground of rocks.. so I think it’s A