As part of a science experiment, Jose did a test for starch on a slice of apple and a slice of potato. The yellow-orange iodine solution stayed the same color when it was put on the apple, but it became black on the potato.

Why did the iodine solution change color on the potato?
A.
The iodine mixed with the colors of the potato so it looked black.
B.
The iodine burned the potato and turned it to ash.
C.
The iodine reacted with the potato to form a new substance.
D.
The iodine evaporated into a gas.