In Which One of the Following Situations Do We Definitely

In which one of the following situations do we definitely have a problem with the reliability of a classroom assessment?

A) Ms.Arthur assesses her students' overall physical fitness on Monday; she then assesses it again the following Monday.Students who perform well one week are not the same ones who perform well the following week.
B) Ms.Benavidez uses a test of mechanical aptitude to determine which students are ready for her physics class.She finds out later that the students who scored worst on the mechanical aptitude test are some of the best students in physics.
C) Ms.Candelaria tells students to study Chapter 14 but mistakenly gives them a test over Chapter 15 instead.
D) For her class of 35 students, Ms.D'Amato devises a test that must be given to students one at a time and requires two hours for each student.