(a) Budding, fragmentation and regeneration are all considered Asexual modes of reproduction because these methods involve only one parent. Asexual reproduction is a kind of reproduction by which offspring arise from a single organism (single parent) and inherit the genes of that parent only. Thus The offspring will be exact genetic copies of the parent. 

Budding is a type of asexual reproduction in which a new organism develops from an outgrowth or bud. 

Fragmentation is also a type of asexual reproduction in which an organism is split into two. 

(b) Regeneration is again a type of asexual reproduction in which organisms can be regenerated from a single parent. 

Regeneration is a form of asexual reproduction. It is the tendency of a simple organism to re-grow its lost parts. Planaria can be cut into the desired number of pieces, and each piece grows through specialized cells into a complete organism.