Morgan's math teacher gives weekly quizzes during class. All of the items on the quizzes are designed to assess students understanding of crucial math concepts, and Morgan is a good student who studies consistently for the class. However, her scores fluctuate a great deal. Some weeks she gets every question right, and some weeks she gets more than half wrong. Given these inconsistent scores, you might wonder whether the quizzes are .a. reliable
b. statistically significant
c. generalizable
d. valid