The law of demand is true for most goods in the economy

Refer to the figure above. What is the price effect of a price reduction from $6 to $4?

A) $300 B) $600 C) $900 D) $1,200

If the price of gasoline goes up, and Jacob now buys fewer candy bars because he has to spend more on gas, this would best be explained by

a. the substitution effect. b. the income effect. c. the highly elastic demand for gasoline. d. all of the above.