By enforcing vendor lock-in laws, the government is attempting to help consumers. The right answer is option C.
A vendor lock-in is the process in economics, when the consumer has no other choice of being dependent to only one product made by only one company/producer. If the consumer finds the same product, but produced by another company, the difference in price is such, that it technically gives no option to the consumer rather than staying with the original company.
Vendor lock-in markets may turn in monopolies, and therefore the number one victim of them is going to be the consumer.