Totipotency refers to the capacity of a -

The correct answer is Option (1) → Cell or tissue to produce whole plant in-vitro.

Option (1) Cell or tissue to produce whole plant in-vitro. — Correct. The option speaks of a cell or tissue growing into a whole plant in vitro (in a test tube). Tissue culture depends on this: an explant, any part of a plant, is grown on a nutrient medium to give whole plants.

Option (2) Bud to generate whole plant. — Incorrect. A bud is a whole organ, not a single cell.

Option (3) Seed to germinate to form new plant. — Incorrect. A seed forms a new plant by the growth of the embryo it already holds; this is normal germination. Totipotency is the capacity of any cell or explant to regenerate a whole plant in a test tube.

Option (4) Root to produce new plant — Incorrect. Regeneration from a root is not the meaning of the term.

NCERT Extract:
Biotechnological Applications in Agriculture – “… As traditional breeding techniques failed to keep pace with demand and to provide sufficiently fast and efficient systems for crop improvement, another technology called tissue culture got developed. … It was learnt by scientists, during 1950s, that whole plants could be regenerated from explants, i.e., any part of a plant taken out and grown in a test tube, under sterile conditions in special nutrient media. This capacity to generate a whole plant from any cell/explant is called totipotency.”