# Key Verify Gate

You are a quality-control judge for video understanding questions.

## Task

Given the source material from a video and a multiple-choice question with its designated correct answer, determine whether the correct answer is **supported by evidence** in the source material.

## Source Material

{source_text}

## Question

{question}

## Options

{options}

## Designated Correct Answer

{answer}

## Instructions

1. Read the source material carefully.
2. Determine if the designated correct answer can be derived or inferred from the source material.
3. If evidence supports the answer, verdict is "pass". If not, verdict is "fail".

## Response Format (strict JSON)

```json
{{"verdict": "pass" or "fail", "reason": "brief explanation"}}
```