Answer: The correct answer is YES it is admissible as evidence of the plumber's fault.
Explanation: An Evidence has probative value if it tends to prove an issue. The testimony of the homeowner of the regarding the plumber's response is a party admission. It is admissible as a hearsay exemption under Rule 801(d)(2)(A) which explains that a statement or statemens made by a party in a case cannot be excluded as hearsay when offered against him by the opponent. As such, the statement is a probative evidence.