the body obtains sugar from food. which system most directly affects blood sugar levels?\nrespiratory\nmuscul…

Brief Explanations:

The digestive system breaks down food into nutrients including sugar. It absorbs sugar into the bloodstream, directly affecting blood - sugar levels. The respiratory system is for gas exchange, the muscular system is for movement and support, and the circulatory system transports substances but doesn't directly break down food for sugar absorption.

Answer:

digestive