What is the simplest action type to run a shell script?

The simplest official GitHub Actions action type for running shell commands or shell scripts is a composite action. Composite actions allow an action author to combine one or more run steps and reusable workflow commands in an action.yml file without needing to package a Docker image or write a JavaScript action. Option B is correct because it directly supports shell-based automation. Option A is heavier because Docker container actions require a container image or Dockerfile. Option D is used when the action logic is written in JavaScript and executed with Node.js. Option C is incorrect because “Bash script action” is not an official GitHub Actions action type. This topic checks custom action types and reuse patterns.