A. external
These types of signals are observed when there is a cut on the body. The epidermal cells lose contact with one another and divide faster until they are in contact once again. After they come into contact, division slows down again.
You didn’t put in the full question with what you were given. I hope this helps show you how to answer the question. Sorry it’s messy
We sprinkle powder on carrom board to make the surface of the board smooth. This reduces the friction between the surface of the carrom board, the striker and the coins. As a result, the coins and the striker can move easily on the carrom board.
I believe that the answer is A, if I am not mistaken!