Answer:
A, B and C
Step-by-step explanation:
A. Adding another researcher to provide ratings will make the study less biased.
B. A quiz or exam will show which students have a better understanding of the math material. Better quiz or exam results show that the site is more effective for a student with or without the supplemental instruction.
C. Having a greater sample size is better because a greater scope of students is covered. Different students have different abilities and learning preferences.
The exponent of x in 4x would be 1.
