[单选题]
A block of mass M slides down il;k4l6kt- ppa frictionless plane inclined at an anglebr. fvvp6)4i y q with the horizontal. The normal reaction force exerted by the plb46 vpi .yrf)vane on the block is
A. $Mg$
B. $Mg \; \sin(q)$
C. $Mg \; \cos(q)$
D. zero, since the plane is frictionless.
