Which of the following visual aids are the most fundamental in presentations
A. Microsoft® PowerPoint presentations
B. data tables
C. charts and graphs
D. facial expressions, gestures, and body language

. a function is a relation in which each input has only one output. in the relation , y is a function of x, because for each input x (1, 2, 3, or 0), there is only one output y. x is not a function of y, because the input y = 3 has multiple outputs: x = 1 and x = 2.