Which factor could NOT contribute to discrepancies in MoCA scores among test-takers?

The factors that lead to discrepancies in MoCA scores are numerous and can vary depending on individual experiences and circumstances. The correct choice indicates that cognitive decline due to age would not contribute to disparities in scores among test-takers. This is because cognitive decline could indeed affect an individual's performance, but since it is a common factor affecting large segments of the population, it does not create discrepancies when comparing scores among different test-takers of varying ages.

On the other hand, familiarity with the test format can lead to better performance for some individuals over others, creating discrepancies as those who know what to expect may score higher. Environmental conditions—such as noise levels, distractions, or variations in lighting—during testing can impact concentration and thus affect performance, leading to different scores. Similarly, the time of day the test is administered can influence a test-taker's cognitive function; for example, some individuals may perform better in the morning compared to later in the day due to personal peak performance times. Each of these factors can introduce variability in test results, but cognitive decline itself, while it may affect an individual's score, does not create discrepancies when comparing across individuals of different ages.