Some private taxi drivers in Crimea equipped their cars with air condi

Conclusion:
if all Crimean taxi drivers equip their cars with air conditioners, they will get larger tips than they do now.
Premise:
Some private taxi drivers in Crimea equipped their cars with air conditioners to make their customers more comfortable during the summer months. Tips received by those drivers from grateful customers were, on average, 5 percent higher than tips they received before they air-conditioned their cars.
Assumption: Making the AC a feature in all taxi's won't compromises the exclusivity of this service. If it is then customers would start taking this for granted and wont pay extra tips.

The argument above depends on which of the following assumptions?

(A) Most passengers tipped better when they rode in a taxi equipped with air conditioning.
[Negate this.Does it weakens the arg. Actually no bec arg is abt getting larger tips than they get now. Sort of trap]
(B) Customers do not generally tend to give bigger tips to drivers of large and spacious taxis than to drivers of smaller taxis. [how spacious taxis r not concern here.]
(C) In the long term, the cost of installing an air conditioner will be more than offset by larger tips.
[This is not a concern here.]
(D) Customers will not take air conditioners for granted and revert to their usual tips if all Crimean taxi drivers equip their cars with air conditioners.
(E) Some Crimean taxi drivers are reluctant to air condition their cars, even if it will increase their tips