(a) If a trustee or a predecessor trustee makes a contract that is within his power as trustee and a cause of action arises on the contract, the plaintiff may sue the trustee in his representative capacity, and a judgment rendered in favor of the plaintiff is collectible by execution against the trust property. The plaintiff may sue the trustee individually if the trustee made the contract and the contract does not exclude the trustee's personal liability.
(b) The addition of "trustee" or "as trustee" after the signature of a trustee who is party to a contract is prima facie evidence of an intent to exclude the trustee from personal liability.
(c) In an action on a contract against a trustee in the trustee's representative capacity the plaintiff does not have to prove that the trustee could have been reimbursed by the trust if the trustee had paid the claim.