Marty is holding a meeting with his staff and volunteers to solicit their ideas for organizational improvement. marty is applying which type of capacity as described by letts

I believe the answer is internal capacity.

In business terms, internal capacity refers to the resources tha exist within company's staffs/employees which can contribute to the growth of the company.

In order to obtain this resources, company could take several approach such as investing in employees skill training and encouraging employees to share their ideas.