Which of the following obligations under UCC 4A may be varied by agreement?

The option regarding "Choice of Law" is indeed correct because UCC 4A allows parties to select the law that will govern their transactions, which can differ from the default provisions set forth in the UCC. This flexibility enables businesses to negotiate terms that best suit their specific circumstances and legal environments, fostering more tailored agreements that align with their operational needs.

In contrast, the obligations related to timely transmittal of entry, notice to the receiver, and receiving final settlement are generally considered to be standardized responsibilities under UCC 4A, which are intended to provide predictability and security in the commercial transaction landscape. These obligations establish a framework within which parties must operate, and they cannot be easily varied by agreement due to the fundamental nature of these responsibilities in facilitating proper and timely payment processing in the ACH system.

Thus, the ability to vary the "Choice of Law" demonstrates the principle of autonomy in contract negotiations, presenting a strategic opportunity for parties engaged in commercial transactions to define the legal context that governs their agreement.