4. Researchers believed that floral scent can sometimes improve a person's learning ability. They set up an experiment in which each of 22 subjects completed sets of mazes. Each subject wore a floral-scented mask and an unscented mask in random order. The researchers measured the time to complete the sets of mazes.
What is the explanatory variable (factor)?
The amount of scent. Presence or absence of the floral scent. Time to complete the pencil and paper mazes. Whether the subject was able to complete the mazes quicker while wearing the floral scented mask.