Why must plants have a constant source of carbon dioxide? A: It is utilized in the process of photosynthesis to make glucose
B: It is the final acceptor at the end of the Calvin cycle.
C: It acts as a coenzyme in the process of photosynthesis.
D: It is utilized in the synthesis of chlorophyll.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

the awnser is d i think