I would say the answer is C. The government
All states require candidates for barber licenses to take and pass a state barber examination, which may be a state-designed examination, the national examination through the National-Interstate Council of State Boards of Cosmetology (NIC), or a combination of the two.
Upon the successful completion of a barber program or apprenticeship, candidates for barber licensure must successfully take a state license examination, which generally consists of a written (theory) section and a practical (hands-on) section. Some states utilize the written and/or practical examinations offered through the National-Interstate Council on State Boards of Cosmetology (NIC).
Well mechanical digestion involves physically breaking the food into smaller pieces but chemical digestion involves breaking down into simpler nutrients that can be used by cells.