Answer: E. Trade customs

Explanation: The privity of contract rule generally states that only those who are parties to a contract can sue or be sued under it. Exceptions to this rule include situations where rights or obligations are conferred upon third parties. For instance:

• Option A (Third party right of action under the Motor Vehicles Act) is an exception because it allows a third party to sue for damages even though they are not a party to the contract.
• Option B (Trustee’s right of action) is another exception, as a trustee can sue on behalf of beneficiaries.
• Option C (Agency with power of attorney) is also an exception since an agent can act on behalf of the principal.
• Option D (Restrictive Covenant) allows third parties to enforce restrictions on property use.

However, Option E (Trade customs) is not an exception to privity of contract because trade customs do not inherently provide a third party with the right to sue or be sued under a contract.