Answer:
The statements " cost of the number of the same articles purchased varying with the number purchased' shows direct variation .
Option (a) is correct .
Explanation:
Definition of the direct variation
When two variables that can be expressed by an equation in which one variable is equal to a constant times the other.
i.e
x = ky
As the x increases than y is also increase .
As given the statement in the question
The cost of the number of the same articles purchased varying with the number purchased.
i.e
As the number of purchased article increases thus cost of the articles also increases .
Therefore the statements " cost of the number of the same articles purchased varying with the number purchased' shows direct variation .
Option (a) is correct .