The correct options are
B At F, motion is in the −x direction.
C At C, velocity is +ve
We know that the slope of the x−t graph represents velocity and the slope of tangent at D is zero so velocity at point D is 0.
At point C, slope is positive due to which velocity is also positive.
At point F, slope is negative due to which velocity is also negative which means that the direction of motion is now in −x direction.