Makenna Is Starting Her First Job as a Teacher

Makenna is starting her first job as a teacher.She is considering how to use goals to effectively encourage persistence and concentration,and to increase student motivation.
Makenna should

A) set goals that are easy to meet so she can reward her students often.
B) not set goals for them because they should be intrinsically motivated.
C) set goals that are very difficult so that students will feel great when they succeed.
D) set challenging and specific goals that are not too difficult or too easy.