We are given that candy Crunchers visited one middle school and one high school in Miami,FL to see if high school students enjoys their candy more or middle school candidates enjoys candy more.
Since they visited only 2 schools and interviewed 100 students in each school, sample will be "all the students who attend one middle school and one high school in Miani,FL".
That is option "A" and sample size is 100+100 = 200 students