[单选题]
A block of mass M sldp.,,ivwtz*; 47ax tqnv nd1d ld;7d(b4nl ka (3. je x1abdayides down a frictionless plane inclined at an angle q with the horizontal. The normal reactidad3an.4lklj a1yd x(eb;b 7(on force exerted by the plane on the block is
A. $Mg$
B. $Mg \; \sin(q)$
C. $Mg \; \cos(q)$
D. zero, since the plane is frictionless.
