The overuse of antibiotics has led to a form of antibiotic resistant tuberculosis. This has occurred ...

The overuse of antibiotics has led to a form of antibiotic resistant tuberculosis. This has occurred as a
  result of:
  a. directional selection within the bacterial population.
  b. stabilizing selection within the bacterial population.
  c. disruptive selection within the bacterial population.
  d. a heterozygote advantage within the bacterial population.
  e. balanced polymorphism within the bacterial population

Question 2

Seriously abnormal phenotypes or harmful mutations are acted against or reduced to low frequenciesby:a.
 
   beneficial mutations.
  b. gene flow.
  c. disruptive selection.
  d. genetic drift.
  e. natural selection.