[单选题]
If you push twice as hard against a stationary brick walgr b:(*5te:ec q xe:hfmiq- z+kaqoc -poq m)k(abvv;pz5+5 3l, the amount of work yoo5azp5qcbop)q+ aziv;3qm -v+ k (k-mu do
A. doubles.
B. is cut in half.
C. remains constant but non-zero.
D. remains constant at zero.
