Mechanical digestion so breaking down of the food in your mouth. Hope this help :)
The correct answer is (a.) Its spindle-shaped cells allow it to do smooth muscles. The structure of the cardiac muscles which is spindle-shaped is very important for the heart to withstand the stretching of the muscles during the contractions. Also for its smooth surface which is very important to prevent any possible blood clot during circulation.
Emphasis made of finding cost effective ways to reduce air pollution.
