Consider two kinesin motor proteins at the mitotic spindle midzone: kinesin A is a tetrameric motor that walks toward the plus end of both microtubules to which it is attached via its motor domains; kinesin B, on the other hand, walks toward the minus end of one microtubule while it is attached to another microtubule via its tail domain. How do these motors affect the length of the spindle? A. They both work to shorten the spindle.
B. Kinesin-5 works to shorten the spindle whereas kinesin-14 works to lengthen it.
C. Kinesin-5 works to lengthen the spindle whereas kinesin-14 works to shorten it.
D. They both work to lengthen the spindle.