A critical activity is. a. an activity that consumes no time but shows precedence between events. b. a milestone accomplishment within the project. c. an activity with zero slack. d/ the beginning of an event.

C

Explanation:

Critical activity is the sequential activities from beginning to the end of a project. A lot of projects have a single critical path, although some projects may have more than one critical activity which depends on the flow logic utilized in the project.