Which of the following describes a valid authority of a trustee?

The correct choice indicates that a trustee has the authority to convey property as specified in the trust agreement. This is a fundamental duty of a trustee, who acts as a fiduciary on behalf of the trust and its beneficiaries. The trustee must follow the specific instructions laid out in the trust document, which often includes the power to sell, transfer, or convey property to fulfill the objectives of the trust. This authority is essential to ensure that the trust operates as intended by the grantor and that the beneficiaries receive the benefits they are entitled to, as outlined in the trust agreement.

In contrast, the other options suggest limited or incorrect scopes of authority for a trustee. Managing trust property and collecting income are part of their responsibilities but do not encapsulate the broader authority associated with conveying property. Additionally, a trustee typically does not have the authority to unilaterally change the beneficiaries of the trust, as this would violate the terms set forth by the trust's creator. Therefore, the ability to convey property, as specified in the trust, is a key authority granted to trustees, making this choice the correct answer.