List and give an example of three different defensive programming practices

Placeholders  are the containers in  layouts  that hold such content as  text  (including body  text, bulleted lists, and titles),  tables,  charts, smartart graphics, movies, sounds, pictures, and clip art.  slide layouts  also contain the theme (colors, fonts, effects, and the background) of a  slide.

Answer/// computers;

(d) context aware computing