Regarding the assertion and reason; choose the correct option.
Assertion [A]: Caecum is a blind sac that contains symbiotic micro organisms.
Reason [R]: E. coli produces vitamin B12, vitamin K, vitamin B1, and vitamin B2.
The caecum houses several bacteria such as E. coli. They constitute the natural bacterial flora of the colon. These bacteria work on the undigested waste and produce vitamins such as vitamin B12, K, B1, and B2 etc., which are reabsorbed through the walls of the colon