18. The mass percent of carbon in a typical human is 18%, and the mass percent of in natural carbon is 1.6 × %. For an 80-kg person, how many decay events per second occur in this person due to the p-particle decay of ? (For , half-life for ẞ-decay is 5730 years.) (A) 2800 (B) 3800 (C) 4800 (D) 5800