Alexander Fleming Observed a Colony of Mold That Inhibited the Growth

Multiple Choice

Alexander Fleming observed a colony of mold that inhibited the growth of nearby bacteria. What was the hypothesis proposed by Fleming to explain this result?

A) The mold was dead.
B) The bacteria changed their DNA when growing near the mold.
C) The mold produced a substance that killed nearby bacteria.
D) The mold used all of the nutrients so that the bacteria couldn't grow.