Answer: A. Specific, difficult goals are best.
Explanation:
A wealth of research such as the Goal-Setting Theory by Edwin Locke have gone into proving that Specific, difficult goals are best for Motivation.
The premise behind this logic is that if you focus on a specific goal, you can channel proper energy to it and can work towards it rather than vague goals.
For example, if you say you're going to write a book by the end of the year. That's a bit vague. If you say however that for 10 hours each week you'll endeavour to write at least 2 chapters of the book, that's Specific and you'll have a better chance of accomplishing that.
