If a bag of fertilizer is labeled “23-19-17”, then it

A. contains 23% N, 19 % K, 17 % P

B. contains 23% N, 19 % K₂O, 17 % P₂O₅                        

C. provides 23 % of P, 19 % of K, and 17 % of plant N needs

D. none of these