Straightening a joint is known as?

Extension

Elevation

Supination

Dorsiflexion

Straightening a joint is known as extension.

Elevation occurs when a structure moves in a superior direction (when a structure moves upward). Supination is rotation of the forearm (so named because the motion uses the supinator and pronator muscles). Dorsiflexion is simply moving the foot upward, toward the tibia bone.

Answer:

Extension