Final answer:
Greg's failure in terms of goal-setting rules likely stems from B) Lack of a specific and achievable goal. His long-term goal of being on the varsity football team may not have been detailed enough or may have lacked smaller, measurable objectives and the ability to adapt to changes, all essential aspects of successful goal-setting.
Step-by-step explanation:
The likely reason for Greg's failure in terms of goal-setting rules is B) Lack of a specific and achievable goal. Goal-setting involves creating targets that are not only specific but also attainable and relevant. Greg's goal to be on the varsity football team by his senior year may have been too broad or potentially unattainable depending on various uncontrollable factors. It's important in goal-setting to outline specific steps and have measurable objectives, something Greg may have overlooked. Moreover, setting a single long-term goal without interim objectives or the ability to adjust expectations might set one up for disappointment if the outcome isn't reached.
Indeed, when setting goals, using the S.M.A.R.T criteria (Specific, Measurable, Achievable, Relevant, Time-bound) enhances the chance of achieving them. Goals must also be flexible to adapt to new situations, and it's essential to set not just ultimate goals but also smaller, attainable objectives along the way.