Participants in a concept learning study 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(n) effect.

a) contrast
b) fatigue
c) practice
d) boredom

(C) Practice

Explanation:

The practice effect are one of the type test result effect that basically occur when the test are taken multiple practices.

This type of effect is basically result into the improvement in the given experimental result by practicing the activities. It also helps in improve the efficiency of the performance.

According to the given question, the leaning study concept is basically result into the practice effect as it helps in solving the various types of puzzles in the given specific time.

Therefore, Option (C) is correct.