Spinach is an inferior good. Popeye's demand curve for Spinach would shift to the right.
Work Step by Step
Since Popeye's income has declined, hence his purchasing power has decreased. As a result, he should demand lesser normal good. Since would not want to spend more amount to maintain the level of his consumption of normal goods, he would shift his preference toward inferior goods like spinach that he can buy with lesser money. Now, since the demand for the spinach has increased, hence, the demand curve would shift to the right.