Which of the Following Is an Application of the Ceteris

Which of the following is an application of the ceteris paribus condition?

A) An analysis of how worker productivity increases when a firm invests in new computers and new training programs for its employees.
B) An analysis of how people purchase more goods when prices decline and income increases.
C) After reading an article on the dangers of high fat diets,an individual buys less red meat when prices increase.
D) An analysis of how price changes affect how much people will purchase when all other factors are held constant.