The dots represent a bacterial infection. sal was very sick with this bacterial infection. the infection was treated with antibiotics. sal seemed to get well, but in a few weeks, she was sick again. how can this be explained using natural selection? a) the antibiotics were ineffective to this strain of bacteria. b) the stronger, more resistant bacteria survived the antibiotics and reproduced. c) the antibiotics did not kill the bacteria; it only forced them to be dormant. d) antibiotics will only kill a portion of the bacteria, no matter how much medicine sal takes.