On a table, three blocks (including the first block) are placed as shown in the figure. Mass of ...

On a table, three blocks (including the first block) are placed as shown in the figure. Mass of each block is \( m \) and coefficient of friction for each block is \( \mu \). A force \( F \) is applied on the first block so as to move the system. The minimum value of \( F \) should be
(a) \( 8 \mu \mathrm{mg} \)
(b) \( 9 \mu \mathrm{mg} \)
(c) \( 7 \mu m g \)
(d) \( 5 \mu m g \)