An oily patch on the blotting paper during the paper test indicates the presence of _______.

The correct option is C

Fats

If food is blotted with a paper, the presence of fats in food makes a transparent patch on the paper. Visible fat is fat that you can see, like butter, margarine, oil and trimmings from meat that forms oily patch on the blotting paper. Invisible fat is fat that is present in food that may be invisible to the eye, like fat in eggs, fish, dairy products, sweets and baked goods.