What would be expected to happen if:
$(a)$ $GA_{3}$ is applied to rice seedlings
$(b)$ Dividing cells stop differentiating
$(c)$ $A$ rotten fruit gets mixed with unripe fruits
$(d)$ You forget to add cytokinin to the culture medium.

(N/A) If $GA_{3}$ is applied to rice seedlings,the seedlings will exhibit internode elongation and an increase in height.
$(b)$ If dividing cells stop differentiating,plant organs such as leaves and stems will not be formed. The mass of undifferentiated cells is called a callus.
$(c)$ If a rotten fruit is mixed with unripe fruits,the ethylene produced by the rotten fruit will hasten the ripening of the unripe fruits.
$(d)$ If you forget to add cytokinin to the culture medium,cell division,growth,and differentiation will not be observed.