Final answer:
The ability to touch your thumb to your fingertips is thanks to the saddle joint between the trapezium carpal bone and the first metacarpal bone at the base of the thumb. This joint provides the thumb the ability to move away from the palm of the hand along two planes. The correct option is c) Saddle joint
Step-by-step explanation:
The ability to touch your thumb to your fingertips is thanks to the saddle joint.
A saddle joint allows two different types of movement. An example of a saddle joint is the first carpometacarpal joint between the trapezium carpal bone and the first metacarpal bone at the base of the thumb.
This joint provides the thumb the ability to move away from the palm of the hand along two planes.
The thumb can move within the same plane as the palm of the hand or it can jut out anteriorly, perpendicular to the palm. This movement of the first carpometacarpal joint is what gives humans their distinctive “opposable” thumbs. The correct option is c) Saddle joint