How do I give an ideal answer to this question?

In self pollinated species, pollination is occuring on the same plant. Geographical isolation can occur only between different organisms. Hence it will not be a major factor for speciation.

Gographical isolation is not a major factor in the speciation of an organism that reproduces asexually since asexual reproduction does not require two organisms to reproduce. It involves only a single organism. Barriers can only form between different organisms. Moreover asexually reproducing organisms pass on the parental DNA to offspring which gives no chance of  speciation.Hence geographical isolation is not a major factor for speciation here.