A petition for the incorporation of a city shall be signed by either of the following:
(a) Not less than 25 percent of the registered voters residing in the area to be incorporated, as determined by the commission pursuant to subdivision (f) of Section 56375.
(b) Not less than 25 percent of the number of owners of land within the territory proposed to be incorporated who also own not less than 25 percent of the assessed value of land within the territory proposed to be incorporated, as shown on the last equalized assessment roll of the county.