Buyer and Seller entered into a written contract. A dispute arose between them, and the Seller sued the Buyer for breaching the contract. At trial, the Seller wants to present oral testimony about telephone calls exchanged between the parties, before they signed the contract, to show that their agreement was different from what is reflected in the written contract. Which of the following contract clauses is likely to be most effective in preventing the introduction of the proposed oral testimony at trial? a. "No amendment to or modification of this Agreement is effective unless it is in writing and signed by an authorized representative of each Party." b. "If any provision of this Agreement is invalid, illegal, or unenforceable in any jurisdiction, such invalidity, illegality, or unenforceability will not affect any other term or provision of this Agreement or invalidate or render unenforceable such term or provision in any other jurisdiction." c. "This Agreement constitutes the sole and entire agreement of the Parties with respect to the subject matter of this Agreement and supersedes all prior and contemporaneous understandings, agreements, and representations and warranties, both written and oral, with respect to such subject matter." d. "Neither party may assign any of its rights or delegate any of its obligations hereunder, in each case whether voluntarily, involuntarily, by operation of law or otherwise, without the prior written consent the other party