Into which chamber of the heart do the superior vena cava

Explanation:

The superior vena cava (SVC) is the superior of the two venae cavae(inferior and superior), the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. The oxygen-poor blood enters the right atrium (RA), or the right upper chamber of the heart.

the way that the mass of carbon can be conserved through cellular respiration is through a process/law called the law of conservation of mass which even tho it undergoes a process, mass is not be destroyed or changed

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.