Answer: (d.) A lump-sum tax which violates the benefits principle.
Explanation:
Here the tax is an amount, i.e. it is lump-sum and it violates benefit principle because they are not taxed according to their willingness to pay.
Also a same fee is charged from all the students irrespective of their level of activity, i.e. a lump sum tax.
Therefore it is violating the benefits principle because the fee is independent of the campus activities. A student might be receiving greater benefits than the other in terms of higher campus activities but is paying the same fee.