A rigid transformation (also called an isometry) is a transformation of the plane that preserves length. In a rigid transformation the pre-image and image are congruent (have the same shape and sizes).
A. A dilation is a transformation that produces an image that is the same shape as the original, but is a different size (not an isometry). Forms similar figures or in other words preserves only angle measurement and ratio between sides lengths. In simple words, dilation means, it just resizes the given figure without rotating or anything else. It is not rigid transformation.
B. A rotation is a transformation in which the object is rotated about a fixed point. The direction of rotation can be clockwise or anticlockwise. Rotation is rigid transformation, it means that rotation preserves sides lengths.
C. In a reflection transformation, all the points of an object are reflected or flipped on a line called the axis of reflection. Under reflection, the shape and size of an image is exactly the same as the original figure. This type of transformation is rigid.
D. In a translation transformation all the points in the object are moved in a straight line in the same direction. The size, the shape and the orientation of the image are the same as that of the original object. Same orientation means that the object and image are facing the same direction. This type of transformation is rigid.
Answer: correct choice is A.
