Answer:
D. 10 N west.
Step-by-step explanation:
Forces along the west and east must be equal to make block static. Let F1 is the force along east, F2 is the force along west. So,
F1=F2
25=15+F
Where, F is the additional force required along west to keep bock in steady state.
F = 10 N west.
Hence, when 10N additional force is applied along west then block will not accelerate.