Explanation:

'Outstanding rent' in accounting contexts is categorized as:

- Option 1: Natural personal account - Relates to individuals or entities, not suitable for 'Outstanding rent.'

- Option 2: Representative personal account - Correct classification, since it represents a liability for unpaid rent owed by the business, standing in place of accounts owed by/to individuals.

- Option 3: Real account - Pertains to tangible or intangible assets, not applicable to outstanding expenses.

- Option 4: Nominal account - Relates to income, expenses, gains, and losses; doesn't represent liability accounts directly.

Option 2 (Representative personal account) is the correct choice