Refer to Goods X and Y. If the indifference curves are downward sloping straight lines (rather than convex curves), then we can conclude that

Assume that good X is on the horizontal axis and good Y is on the vertical axis in the consumer-choice diagram. PX denotes the price of good X, PY is the price of good Y, and I is the consumer's income. Unless otherwise stated, the consumer's preferences are assumed to satisfy the standard assumptions.

a. X does not affect the individual’s utility.
b. Y does not affect the individual’s utility.
c. both X and Y affect the individual’s utility.
d. neither good affects the individual’s utility.

c. both X and Y affect the individual’s utility.