The correct option is (b) growth movements.
Explanation:
Clinostat/klinostat is an instrument which can nullify the effect of gravity and allow a plant to grow horizontally by slowly rotating it. Rotating clinostat do not show any bending because the gravitation stimulus in this case is not unilateral as it affects all the sides of the rotating organs. equally, whereas plant kept in unrotatedl/fixed clinostat bends downwards showing positive geotropism.