Pass the Claude Certified Architect exam

Answer: D. Read-heavy research where independent sources can be explored simultaneously and each subagent returns a condensed summary

Parallel subagents shine on parallelizable, self-contained, read-heavy work: each worker explores independently in its own context and returns compressed findings. Sequential dependencies eliminate the parallelism benefit, tasks requiring continuously shared state incur heavy coordination overhead, and quick targeted edits are better done in the main conversation because subagents start fresh and add latency.

Answer: A. The tool call is blocked, and the hook's stderr output is fed back to Claude as an error message

Exit code 2 from a PreToolUse hook is a blocking error: the tool call is prevented and the stderr text is returned to Claude so it understands why the action was rejected. Stdout, including any JSON, is ignored on exit code 2; JSON decisions like permissionDecision are only processed when the hook exits with code 0. There is no automatic retry behavior for hooks.

Answer: D. Gather context, take action, verify work, then repeat.

Anthropic describes the agent loop as gathering context, taking action, verifying work, and repeating until the task is done. Classify-and-route describes the routing workflow, not the agent loop, and generate-then-evaluate describes evaluator-optimizer. Planning everything upfront and terminating contradicts the iterative, feedback-driven nature of agents.