A plant cell has potential to develop into a full plant. This is called as 

$\text{Correct option: }$ A

$\text{ Solution: }$

$\text{ Option (a): }$

$?$Totipotency is defined as the ability of a single cell to divide and produce into the cell which can perform different functions due to differentiation.

$\text{ Option (b): }$

$?$Gene cloning is the technique used for generating multiple copies of a particular gene. 

$?$This particular gene of interest is located and copied or cloned from the DNA mixture extracted from the organism. 

$?$It is carried out to obtain gene products in larger quantities.

$\text{ Option (c): }$

$?$The method of biological research which allows the transfer of  fragments of tissue from an animal or plant into an artificial environment for development and survival is considered as tissue culture. 

$\text{ Option (d): }$

$?$Regeneration is the natural process  of reviving the damaged cells naturally. 

$?$It makes all the plants and animal tissue functional again. 

Hence, the correct answer is option (a).