Which of the Following Will Increase the P/E Ratio, Everything

Which of the following will increase the P/E ratio, everything else being constant?
I. A decrease in the number of shares outstanding
II. An increase in net income
III. A decrease in the earnings yield
IV. A decrease in the market price per share

A) I.
B) III.
C) II and IV.
D) I and III.
E) I, III and IV.