Choose the omitted word in the given sentence from the options given below:

There is a popular belief that by playing music in the background, learning and retention ______ enhanced.

can be

The correct answer is Option (3) - can be

• The sentence would read: "There is a popular belief that by playing music in the background, learning and retention can be enhanced."
• The phrase "can be" indicates the possibility or potential for enhancement, which fits the context of the belief.

OTHER OPTIONS

• "must be" → Implies certainty, which is too strong for this context.
• "should" → Suggests a recommendation or expectation, but not a possibility.
• "may be" → While it suggests possibility, "can be" is more appropriate for the context of enhancement.