Block A, with Mass M_A, Is Initially at Rest on a Horizontal

Multiple Choice

Block A, with mass m_A, is initially at rest on a horizontal floor. Block B, with mass m_B, is initially at rest on the horizontal top surface of A. The coefficient of static friction between the two blocks is $\mu$ _s. Block A is pulled with a horizonatal force. It begins to slide out from under B if the force is greater than:

A) m_Ag
B) m_Bg
C) $\mu$ _sm_Ag
D) $\mu$ _sm_Bg
E) $\mu$ _s ( m_A + m_B) g