Final answer:
Ryan performed a rotation transformation by turning the pattern one fourth turn clockwise. Rotation involves turning a figure about a center point without altering its size or shape.
Step-by-step explanation:
When Ryan decided to rotate the pattern one fourth turn clockwise, he performed a rotation transformation on the pattern. This type of transformation involves turning a figure about a fixed point, often called the center of rotation. Unlike a translation, which slides a figure in a given direction, or a reflection, which flips a figure over a line, a rotation turns the figure without changing its size or shape. A dilation, the fourth option, changes the size of the figure. The correct answer to what transformation Ryan performed is therefore (c) Rotation.