17. When a certain net force is applied to one brick on a frictionless surface, it accelerates at 6 m/s²
When the same net force is applied to three bricks that are cemented together,
A. they accelerate at 3 m/s².
B. they accelerate at 6 m/s².
C. they accelerate at 18 m/s².
D. they accelerate at 2 m/s².
E. they do not accelerate at all.