Answer: B, Width
Step-by-step explanation:
First, what is Friction?
Friction is the force resisting motion. The less friction, the easier it is to get something into motion. For example, moving a 100-pound block of wood is quite difficult. However, slap some wheels on the bottom, and it's much easier. This is because the wheels reduce friction.
Let's look at all of the answer choices closely to determine which one affects friction.
Choice A and D- Odor and Color
Odor and Color do not affect friction in any way, shape or form. Friction, again, is the force acting against any type of motion. They aren't connected to the motion we need for friction (unexpected rhyme :) .
Choice C - Hardness
Hardness is a material's ability to withstand exterior physical trauma. Which there some evidence connecting this to friction, there is no real, concrete evidence, so this is ruled out by the more obvious answer.
The correct Choice B - Width
The more width, the more area. The amount of surface area between 2 objects plays a role in the amount of friction involved. Because there is more area to rub against, there will be more friction.