Classification of joints is based on

A) their location in the body.
B) the presence or absence of tendons.
C) their ability to move.
D) the length of bones concerned.
E) the type of muscles attached.

Classification of joints is based on their ability to move, which includes the amount and direction of movement. This leads to the grouping of joints into different types such as hinge joints, pivot joints, ball-and-socket joints, etc.