The answer is e. Equilibrium price increases.
A rightward shift in the demand curve indicates an increase in demand, not a change in supply conditions. More favorable supply conditions would typically shift the supply curve, not the demand curve.
A fall in consumers' incomes would generally lead to a leftward shift in the demand curve for normal goods, as people would have less money to spend. A rightward shift suggests an increase in demand, which could be due to an increase in consumers' incomes.
If the price of complementary goods increased, the demand for the commodity in question would likely decrease, leading to a leftward shift in the demand curve. A rightward shift suggests that the price of complementary goods has decreased or other factors have increased demand.
A rightward shift in the demand curve typically leads to an increase in the equilibrium price, as higher demand at the same supply level usually results in a higher price.
When the demand curve shifts to the right, it indicates an increase in demand. Assuming the supply remains constant, this increased demand will lead to a higher equilibrium price as consumers are willing to pay more to obtain the commodity.