Which of the following DATA steps will run without errors?

data a_1;
  set sashelp.class;
  bmi = weight / height ** 2;
  if bmi >= 20;
run;

data a_2;
  set sashelp.class;
  bmi = weight / height ** 2;
  where bmi < 20;
run;

Note: Assumed that the above code executed in a clean SAS session.