Come up with a question and reasoning that would justify this answer: Grant Goodeve

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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The question is: For the show's first two seasons, an upbeat instrumental piece written by Fred Werner was used as the show's opening theme. Beginning with the show's third season, this was replaced by a slowed-down vocal theme titled "Eight Is Enough," which was sung by series co-star Grant Goodeve. The song had music by Lee Holdridge and lyrics by Molly-Ann Leikin, and was first heard in a longer arrangement on the last episode of the second season titled "Who's on First?", which was also performed by Goodeve.

Answer this question based on the passage: who sang the eight is enough theme song?
Step-by-step reasoning process: This is the relevant information: Beginning with the show's third season, this was replaced by a slowed-down vocal theme titled "Eight Is Enough," which was sung by series co-star Grant Goodeve.
