Final answer:
A human hair with a thickness of 70 micrometers is equal to 70 x 10^-6 meters. Therefore, the correct answer is B. 70 x 10^-6 m.
Step-by-step explanation:
The question asks how to express the thickness of human hair in meters, given that the hair has a thickness of about 70 micrometers (μm). The correct conversion would recognize that one micrometer is equal to 10-6 meters. Thus, 70 micrometers is the same as 70 x 10-6 meters. Using scientific notation, it can be written as 7.0 x 10-5 meters, but since it's not one of the offered options, the closest correct answer is B. 70 x 10-6 m.