If Instead of a Per-Unit Subsidy, the Government Offered to Pay

If instead of a per-unit subsidy, the government offered to pay for half the good's price, no matter the price:

A) the wedge method would no longer work.
B) instead of a parallel shift in demand, the subsidy should be modeled as a demand curve that is twice as steep.
C) demand would be perfectly elastic.
D) there would be no change in how we model the subsidy.