For the first one the price per ounce is:
$4.56/15oz=0.304 dollars per ounce, which rounds to 0.3
For the second:
$5.98/25oz=0.2392 dollars per ounce, which rounds to 0.24
The second is the cheapest price per ounce and rounds to $0.24/oz so 0.24 is the answer