In a population of bacteria, how does presence of an antibiotic help resistant cells within that population?
A. the antibiotic kills or inhibits competitors, allowing the resistant cell to grow without competition
B. the antibiotic is metabolized by the resistant cell, providing more energy for growth
C. the sensitive cells must devote energy to destroying the antibiotic, slowing their growth
D. the antibiotic mutates sensitive cells, making them incapable of growing