Which of the following is NOT one of the three fundamentals of good marksmanship?

The three fundamentals of good marksmanship are typically recognized as proper sight adjustment or patterning, proper shooting technique, and consistent practice. Option C, which suggests using the largest caliber available, does not align with these fundamentals.

In marksmanship, effective shooting is influenced by the shooter's ability to control their firearm and understand its operation, which is encapsulated in the other three choices. Proper sight adjustment ensures that the shots hit the target accurately, proper shooting technique involves the shooter’s stance, grip, and breathing, and practice builds muscle memory and enhances skills over time. Using a larger caliber does not necessarily contribute to better marksmanship; in fact, it can complicate shooting due to increased recoil and may not be appropriate for every shooter or situation. Therefore, it is not considered a fundamental of good marksmanship.