What substance plays a vital role in maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function?
a. fats
b. fibers
c. proteins
d. carbohydrates

What makes the yardstick test a direct measurement of reaction time? a. the further the yardstick falls, the slower the reaction time. b. yardsticks have numerical markings for length. c. yardsticks are designed to measure reaction time. d. all of the above select the best answer from the choices provided.