Which of the Following Are Good General Cleaning Principles

Which of the following are good general cleaning principles?
1) Always start cleaning in the least contaminated area and clean toward the most contaminated area.
2) Always clean from the bottom to the top.
3) Always clean from the most contaminated area to the least contaminated.

A) 1 and 2 only
B) 1 and 3 only
C) 2 and 3 only
D) 1, 2, and 3 only