How is a front defined in terms of weather? a the leading edge of an anticyclone low b the trailing edge of a warm front c the physical boundary between two or more air masses d the stationary boundary between a warm and cold air mass

A weather front is a physical boundary and is a transition between air masses of different densities. It can be classified as cold, warm, stationary or occluded.

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.