Final answer:
In engineering study, all of the given factors are important to varying degrees, but if we have to select the least important key, it would be ability.
Step-by-step explanation:
In engineering study, all of the given factors are important to varying degrees, but if we have to select the least important key, it would be ability (option c).
Attitude (option a) is crucial as it influences a student's motivation, perseverance, and approach to problem-solving in engineering.
Pre-college preparation (option b) is essential because it provides the foundational knowledge and skills required for success in engineering study.
Effort (option d) is also important as it determines the level of dedication, hard work, and time investment a student puts into their engineering studies.
However, it is worth noting that while ability may be considered the least important factor, it is still necessary to have a certain level of aptitude and skill to understand and apply engineering concepts effectively. Ultimately, it is a combination of all these factors that contributes to success in engineering study.