Two wooden blocks are moving on a smooth horizontal surface such that the mass \[m\] remains stationary with respect to the block of mass M as shown in the figure. The magnitude of force \[p\]is

• A. \[(M+m)g\,tan\,\beta \]
• B. \[g\,\tan \,\beta \]
• C. \[mg\,\cos \,\beta \]       
• D. \[(M+m)g\,\cos ec\,\beta \]