Final answer:
The word 'helpful' is not an action verb; it is an adjective that describes a noun, unlike 'planned,' 'assisted,' and 'developed,' which are verbs that denote action.
Step-by-step explanation:
The item in the list which is not an action verb is e. Helpful. Action verbs express specific physical, mental, or emotional activities performed by a subject. In contrast, 'helpful' is an adjective, which describes a characteristic or quality of a noun, rather than an action.
- Planned
- Assisted
- Developed
- Helpful
Words like 'planned,' 'assisted,' and 'developed' are verbs that illustrate actions someone might perform, whereas 'helpful' does not fit this category as it does not represent an action.