All of the options mentioned can contribute to a person's overall well-being in different ways, but if we focus specifically on positive mental well-being, the option that aligns more directly is:
B. ability to work productively in school
Having the ability to work productively in school can indicate a person's engagement, focus, and capacity to learn and acquire knowledge. It suggests a sense of accomplishment, personal growth, and a positive attitude towards education, which are factors associated with positive mental well-being. However, it's important to note that mental well-being is a multifaceted concept and can be influenced by various factors beyond those listed in the options.