Final answer:
The best first step is meeting with administrators to discuss the garden project's purpose and scope option (c), ensuring school leadership support before involving stakeholders or seeking donations.
Step-by-step explanation:
The best first step in the teacher's action plan for building a garden on school property would be C. Meeting with administrators to talk about the purpose and scope of the project.
Prior to community engagement or requesting donations, it is critical to ensure that the school leadership is on board with the initiative and agrees with its goals and logistics.
Discussions with administrators can provide the necessary approvals and support for further actions such as involving stakeholders, defining project scope, and allocating space and resources for the garden.