A Population of Flights Can Be Classified According to Two

Multiple Choice

A population of flights can be classified according to two factors: duration (short, medium, or long) and purpose (vacation or business) . We are interested in whether either of these factors has an effect on price. The table below gives mean prices for a balanced population. A medium-distance business flight costs $300 more than a short-distance business flight. However, a medium-distance vacation flights is only $200 more than a short-distance vacation flight. This difference between business and vacation flights is called:

A) interference of effects.
B) confusion of effects.
C) difference of effects.
D) interaction.