Final answer:
A deterrent control discourages undesirable actions and thus would match option b. Deterrent in the context of the tragedy of the commons. Preventing free riding and encouraging altruism are techniques that can discourage overuse of common resources and encourage sustainable use.
Step-by-step explanation:
The control category that discourages an incipient incident is b. deterrent. A deterrent control is designed to discourage undesirable actions by making potential offenders aware of the negative consequences of their actions. In the context of the tragedy of the commons, a technique that resonates with this approach is a. preventing free riding, as it is about putting measures in place that discourage individuals or groups from overusing and depleting common resources without contributing fairly to their maintenance or replenishment. Encouragement of b. altruism can also play a role in mitigating the tragedy of the commons by promoting a sense of responsibility and collective well-being that leads individuals to act in the interest of the larger group rather than pursuing selfish gains at the expense of others.