The correct option is Use echo to append VAR=value to the GITHUB_ENV file.

Writing the variable assignment to the special environment file makes that variable available to all subsequent steps in the same job. GitHub Actions reads this file after the step finishes and exports those values for later steps. This is the supported way to persist environment variables across steps within a job.

Manually pass the variable as an argument to every later step is not required and it is fragile. It does not create a true environment variable that is automatically available and it forces you to thread values through each step one by one.

Run export VAR=value within the step only affects the current shell for that step. Each step runs in a new process so the exported value will not be present in later steps.

Write VAR=value to GITHUB_OUTPUT and treat it as a step output is meant for defining step outputs. Those values must be consumed through the steps context and they do not become environment variables for later steps by default.

Full AWS Practitioner Certification Question