The most basic forms of are walking and running.
a. completing a marathon
b. locomotion
c. getting to school
d. biomechanics

b. locomotion

Explanation:

"Locomotion" is one form of movement that moves the body from one point to another or allows it to travel in general space. It develops the person's bodily control. The most basic forms of this movement are "walking" and "running."  

Walking is considered a slower kind of locomotor skill while running is considered a faster kind of locomotor skill. Other skills include: jumping, galloping, skipping, leaping, etc.

this is not an education question