Locomotion And Movement

Repeated activation of the muscles can lead to the accumulation of lactic acid due to anaerobic breakdown of glycogen in them, causing fatigue

Answer (b) Vertebrae

A fracture of the distal end of radius in which the distal fragment displaced posteriorly is called Colles' fracture.

Theoretically, human vertebral column consists of vertebrae - cervical, thoracic, lumbar, sacral and coccygeal. However, it consists of bones as five sacral vertebrae fuse to form one sacrum and four coccygeal vertebrae fuse to form one coccyx.