A developer is writing code that requires making callouts to an external web service.

In Salesforce, a callout cannot be made directly from an Apex trigger (Option C). This is a fundamental architectural restriction of the platform. Triggers execute as part of a database transaction. If a trigger were allowed to make a synchronous callout, the database transaction—along with all its associated row locks—would remain open while waiting for a response from the external system. This could lead to severe performance bottlenecks and transaction timeouts.

To perform a callout based on a trigger event, the developer must move the callout logic into an asynchronous context, such as a @future(callout=true) method, a Queueable class, or by publishing a Platform Event.

Option A is incorrect because while asynchronous methods allow for higher CPU time, they do not extend the maximum individual callout timeout (120 seconds). Option B is incorrect because REST is simply a protocol and does not dictate synchronicity. Option D is incorrect because the limit for callouts in a single transaction is 100, so 10 callouts would still be permissible in a synchronous context (assuming they aren't in a trigger). Consequently, the presence of a trigger is the only factor listed that programmatically mandates an asynchronous approach.