Question

what type of knowledge is crucial for nursery workers?
how to care for plants
business administration
chemical expertise

Explanation:

Nursery workers are responsible for the cultivation, maintenance, and care of plants. Therefore, knowledge about how to care for plants is fundamental to their role. Business administration might be relevant for managing a nursery as a business, but it is not as directly crucial as plant - care knowledge. Chemical expertise could be a part of plant care (e.g., using fertilizers or pesticides), but it is a subset of the broader knowledge of plant care.

Answer:

how to care for plants