Two people push from opposite sides on adjacent blocks that are placed on a rough floor: a $4$ kg block on the left and an $8$ kg block on the right. Throughout this scenario the blocks stay in contact but are not glued together.

Person $1$ pushes down and to the right on the $4$ kg block with force $F_1=12N$ at an angle $=30$ above the horizontal. Person $2$ pushes to the left on the $8$ kg block with a horizontal force $F_2.$

The blocks do not move. What must be the direction of the static friction acting on the two$-$block system?

$($a$)$ The static friction force points to the left.

$($b$)$ No static friction is needed for the blocks to stay at rest.

$($c$)$ The static friction force points to the right.