Change in species is described as a process that usually occurs over long periods of time. Yet, even though antibiotics have only been widely used for fifty years, scientists recognize that overuse of antibiotics has led to antibiotic-resistant strains of bacteria. The reason this can occur in a relatively short span of time is that:.
a. there are many different types of bacteria.
b. bacteria are very small.
c. travelers carry bacteria around the world.
d. bacteria reproduce rapidly.