Participants Solve Several Anagram Puzzles Over the Course of 30

Multiple Choice

Participants solve several anagram puzzles over the course of 30 minutes.Even though the puzzles were known to be of equal difficulty,participants solved the puzzles in less and less time as the 30-minute period progressed.This is likely the result of a _____ effect.

A) contrast
B) fatigue
C) practice
D) boredom