Final answer:
The concept aligns with McClelland's theory, which suggests individuals with a high need for achievement seek moderately challenging tasks to fulfill their sense of accomplishment.
Step-by-step explanation:
The concept that individuals with a high need for achievement prefer to work on tasks of moderate difficulty is consistent with McClelland's theory. David McClelland's theory focuses on how the need for achievement drives individuals to seek challenges that are not too easy or too hard, but instead are sufficiently challenging to be achievable and provide a sense of accomplishment upon completion. The need for achievement is one of the three needs he identified, alongside the needs for affiliation and power.