The rationale is that the upfront, fixed costs of contesting a constituency are likely to be much higher than the additional costs associated with having each additional candidate on that list.
Opsiwn 2 - y dylid cyfrifo'r terfyn costau sy'n gysylltiedig â sefyll mewn etholaeth yn seiliedig ar nifer yr ymgeiswyr y mae'r blaid yn eu sefyll yn yr etholaeth honno.