They were also tasked with answering two questions each, one from the Prime Minister, the other from the National Party President, but neither men was at last night's event.
After which, 101 voting delegates cast their vote and selected Mr Muller as the new candidate.
Last night's event was hosted by Peter Osborne, regional chair of the Central North Island National Party.
National Party Bay of Plenty electorate chair Mark Bayly said Mr Muller and Mr Morris were two "exceptionally good candidates".
"It's been a strong contest," he said.
"Each have got their differences in terms of where they've got unique skill sets and they have both played a skilled and clean race.
"It has been a very robust process."
It is thought that Mr Muller is virtually assured of a seat in Parliament because of the 18,000 vote majority built up by Mr Ryall, 49, who is retiring from politics to take employment in the private sector.