Final answer:
The term 'not very serious' is synonymous with 'Minor', as it describes conditions or events that are not severe. Glaucoma is a serious eye condition, and angioplasty is a serious procedure, whereas ESI level does not pertain to medical severity.
Step-by-step explanation:
The term 'not very serious' can be best matched with the term Minor (Option B). This is because 'minor' describes conditions, illnesses, or events that are not very serious or severe in nature. In contrast, Glaucoma (Option A) is a serious eye condition that can lead to blindness if untreated. Angioplasty (Option C) is a medical procedure utilized to open blocked coronary arteries, which is also serious. Lastly, ESI level (Option D) does not pertain to the severity of a medical condition, but rather to an educational proficiency standard (Economic and Social Research Institute) and does not fit the context of the question.