A direct variation is a mathematical relationship between two variables that can be expressed by an equation in which one variable is equal to a constant times the other. In other words, a direct variation is where

.
In answer a,

, so it is a direct variation.
In answer c,

, so it is a direct variation.
In answer d,

, so it is a direct variation,
Only answer b is left, which means the answer must be 'b'.
We also know 'b' is the answer because it cannot be expressed as <span>

. Instead, it is expressed as </span>

, which is not the same thing and is therefore not a direct variation.
Hope I helped, and let me know if you have any questions :)
Answer:
1
Step-by-step explanation:
The smallest positive factor is 1
But not 0 because 0 is not positive nor negative
The numbers are 1 and 2
1 squared = 1 because 1 x 1 = 1
2 squared = 4 because 2 x 2 = 4
4 - 1 = 3