Two wooden blocks of masses M and m are placed on a smooth horizontal surface as shown in figure. If a force P is applied to the system as shown in figure such that the mass m remains stationary with respect to block of mass M, then the magnitude of the force P is

Question

$$(a)\;(M+m) g\;\tan \beta \quad (b)\;g\;\tan \; \beta \quad (c)\;mg\;\cos\; \beta\quad (d)\;(M+m)\; g\;cosec \;\beta$$