alexkozhura
I have a problem with A. Let's try to negate it.
Let's imagine that our sales are 0. We start offering free trials. 10 users try our product, and 4 of those 10 buy it later. A is negated (there are indeed more people who got the product for free then those who have chosen to pay for it: 6 v. 4), but our sales still have increased by 4 (from 0 to 4).
Therefore, negating A doesn't ruin the argument. Either there must be a better answer choice, or the question is flawed.
We are looking for the conclusion of the argument. Negating the option is used when we are looking for an assumption.
Anyway, since we are looking for the conclusion, negating the correct option is equivalent to negating the conclusion here.
(A) The number of people who see the free trial as an acceptable replacement for buying the online service is not greater than the number of people who buy the online service because of their experience within the free trial.
There are two scenarios: "No free trial" vs "Give free trial"
The argument says that "give free trial" gets more business.
"Give free trial" works in two ways -
One, there are people who would have bought the product in "no free trial" scenario but after using the free trial, they don't feel the need to buy it anymore. For example, think of a video game. User X would have bought it but he played the game in the trial version and was satisfied. He doesn't need to buy it anymore. So this will decrease the potential sale.
Two, there are people who wouldn't buy the product in "no free trial" scenario. But they see the free trial and enjoy their experience with it so they buy it. This increases the sale.
Since the argument is telling us that "give free trial" gets more business, we know that the second point trumps over first. This is what (A) is saying - that second point has more impact (people) than the first.
The comparison is not between people who buy and those who don't after checking the free trial (as you suggested)
It is between those who would have bought without free trial but did not with free trial and those who would not have bought without free trial but did after free trial.