Explanation:

- Option 1: much

- This is the correct choice. "Much" is often used to emphasize comparative adjectives like "poorer." It suggests a significant difference.

- Option 2: very

- "Very" is usually used with simple adjectives (e.g., very rich) and doesn't suit comparative forms like "poorer."

- Option 3: more

- "More" would make sense if comparing two items directly (e.g., "more poor than one friend"). It doesn't fit well in this context.

- Option 4: most

- "Most" is used for superlatives and suggests being at the top of a certain group. It wouldn't fit when directly comparing him to all his friends collectively.