(A) Storage device
(B) Output device
(C) Input device
(D) Programming language

A trackball is a pointing device that consists of a ball housed in a socket containing sensors to detect rotation of the ball. The user can move the cursor on a computer screen by rotating the trackball with their fingers or palm. Trackballs are an alternative to traditional computer mice and are used for various applications, including gaming, graphic design, and other tasks that require precise cursor control.