Which of the following safety and effectiveness exercise factors considers the speed and control of an exercise?
a. alignment
b. biomechanics
c. momentum
d. stability

Among the safety and effectiveness factors stated above, the one that considers speed and control the most would be stability. Although alignment can also be a factor, alignment is a factor of stability. For the safety of the user when exercises are done, it is important that the body is stable when doing the full range of motion of an exercise. Doing an exercise too fast while being unstable will cause injury.