The order of the adjectives in the given sentence is wrong. Please select the option that suggests the correct order:
My sister has a plastic small purple box.
We can use several adjectives to describe a single noun. But when we use adjectives of different kinds together they usually follow an order. The commonly followed order would be size, quality, colour, origin and substance. The noun in the sentence is ‘box’, and the adjectives that describe it are ‘plastic’ which is the substance it is made of, ‘small’ which describes the size of the box, and ‘purple’ which indicates the colour. Hence based on the order of the adjectives it has to be ‘size, colour and substance’, i.e. ‘small purple plastic box’. Therefore option C is correct, whereas options A, B and D are incorrect.