Which observation do most scientists think supports the big bang theory as a description of the origin of the universe? a. our sun is a yellow star. b. the universe appears to be expanding. c. stars that vary in luminosity exist. d. stars change their positions in the sky.

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.