I'll try to explain, because I've had tubes before. In fact, I still have them.
For me, tubes were put in because of too many ear infections, and excessive water in my ear. The tube helped drain the water out. You can see A picture I have in a file. The tubes can be put I believe in the ear drum. They're put there to help drain water that has trouble getting out on its own.
<u>Solu</u><u>tion</u><u> </u><u>:</u><u>-</u>
In biology the word <em>bio</em><em> </em><em>catylysts</em><em> </em>describes the word enzymes . Bio catylysts are nothing but enzymes which alter the rate of reaction . For ex - Pepsinogen , which is produced in the stomach of humans activated by HCl from a proenzyme called trypsin . It works in acidic medium and converts proteins into peptides and protons . Likewise there is another enzyme called Salivary amylase which is present in the saliva of humans converts starch into maltose . There is another enzyme called lipase which converts fats into fatty acids and glycerol .
The answer is C since heterotroph means they don't have a way of making food