Which Set of the Following Strategies Do Researchers Conducting Quantitative

Which set of the following strategies do researchers conducting quantitative research use to assure reaching correct conclusions from their statistical analysis?
1) Eliminate chance variation as an explanation
2) Use statistics based on the normal curve
3) Avoid low statistical power
4) Control extraneous variables
5) Use categorical measurements
6) Control bias

A) 1, 2, 3, and 4
B) 1, 3, 4, and 6
C) 2, 3, 4, and 5
D) 1, 2, 5, and 6