Caleb Is 12 Years Old and as Part of an Ongoing

Multiple Choice

Caleb is 12 years old and as part of an ongoing research study he has been assessed for "creativity" every six months for the past six years.Now that Caleb understands what is expected on the test,his answers have become more creative and he achieves higher scores.What accounts for Caleb's increased performance?

A) selective attrition
B) observer influences
C) cohort effects
D) practice effects