Whenever People's Incomes Increase,they Buy More Guitars

Whenever people's incomes increase,they buy more guitars.Hence a scatter diagram shows that the relationship between income and guitars purchased is

A) a positive relationship.
B) some sort of relationship,but whether it is positive or negative depends on whether income is plotted on the vertical or horizontal axis.
C) a linear relationship.
D) a negative relationship.
E) a U-shaped relationship.