Food starts to move through your GI tract when you eat. When you swallow, your tongue pushes the food into your throat. A small flap of tissue, called the epiglottis, folds over your windpipe to prevent choking and the food passes into your esophagus.
Esophagus. Once you begin swallowing, the process becomes automatic. Your brain signals the muscles of the esophagus and peristalsis begins.
Lower esophageal sphincter. When food reaches the end of your esophagus, a ringlike muscle—called the lower esophageal sphincter —relaxes and lets food pass into your stomach. This sphincter usually stays closed to keep what’s in your stomach from flowing back into your esophagus.
Stomach. After food enters your stomach, the stomach muscles mix the food and liquid with digestive juices. The stomach slowly empties its contents, called chyme, into your small intestine.
Small intestine. The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine, and push the mixture forward for further digestion. The walls of the small intestine absorb water and the digested nutrients into your bloodstream. As peristalsis continues, the waste products of the digestive process move into the large intestine.
Large intestine. Waste products from the digestive process include undigested parts of food, fluid, and older cells from the lining of your GI tract. The large intestine absorbs water and changes the waste from liquid into stool. Peristalsis helps move the stool into your rectum.
Rectum. The lower end of your large intestine, the rectum, stores stool until it pushes stool out of your anus during a bowel movement.
        
             
        
        
        
My best guess would be c because b makes no since we as humans do not have photosynthesis and are considered living organisims, d is also wrong because the brain requires oxygen, and its not a because the brain is made of cells.
        
             
        
        
        
Answer:
A sudden shortage of goods is called a shortage and happens for a variety of reasons in economics.
 
        
             
        
        
        
The answer is bioaccumulation. Bioaccumulation is when toxins build up in a food chain. The animals at the top of the food chain are affected most severely because the concentration of toxin becomes most concentrated in the body tissues of the animals at the top of the food chain.