Which of the following is a type of snaffle bit commonly used in horse riding?

The full cheek snaffle is indeed a commonly used type of snaffle bit in horse riding. This particular design features extensions, or "cheeks," that help to provide lateral control of the horse's head. The full cheek allows for better communication and prevents the bit from being pulled through the horse's mouth, making it particularly useful for young or inexperienced horses who are still learning to respond to the bit.

The design of the full cheek snaffle enables a rider to apply more consistent pressure through the reins without the bit sliding out of position, which is beneficial for training purposes. Riders often choose this type of snaffle for its effectiveness in teaching horses to respond appropriately to the bridle without harshness.

Other options presented, such as the western bridle, spade bit, and curbed bit, are distinct types of bits or equipment that serve different purposes and are not classified as snaffle bits. While each of those bits has its place in equestrian practice, the full cheek snaffle is the clear choice as a type of snaffle bit used for direct control and communication during riding.