Three blocks \( A, B \) and \( C \) are lying on a smooth horizontal surface, as shown in the fi...

Three blocks \( A, B \) and \( C \) are lying on a smooth horizontal surface, as shown in the figure. \( A \) and \( B \) have equal masses \( m \) while \( C \) has mass \( M \). Block \( A \) is given an brutal speed \( v \) towards \( B \) due to which it collides with \( B \) perfectly inelastically. The combined mass collides with \( C \), also perfectly inelastically \( \frac{5}{6} \) th of the initial kinetic energy is lost in whole process. What is value of \( M / m \quad \) [JEE (Main) 2019]
(a) 2
(b) 4
(c) 5