Read the paragraph and answer the questions:

Plant tissue culture is based on the special property of plant cells to generate a whole plant, called totipotency. The plant part used in tissue culture is called explant. The nutrient medium provides a carbon sources such as sucrose. inorganic salts, vitamins, amino acids and growth regulators like auxins cytokinins etc. Propagation of thousands of plants in very short duration through tissue culture is called micropropagation. Each of these plants will be genetically identical to the original plant i.e., they are somaclones. Another application of tissue culture is to recover virus free plants, from the infected ones. The apical or axillary meristem, which is free of virus, is removed and cultured in-vitro to obtain virus-free plants. Scientists have succeeded in culturing meristems of sugarcane, banana, potato etc. Scientists have isolated single cells from plants and after digesting their cell walls. the protoplasts were isolated. Protoplasts from two different varieties of plants - each having a desirable character - are fused to get hybrid protoplasts. These hybrid protoplasts are called somatic hybrids and the process is called somatic hybridisation. Somatic hybrids are further grown to form a new plant. Protoplast of tomato is fused with that of potato, to form new hybrid plants called Pomato. Pomato unfortunately did not have all the desired combination of the two plants.

The explant used in tissue culture must show : 

Totipotency

The correct answer is Option (4)- Totipotency

In tissue culture technique , any part of a plant is  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. It is important to note that the nutrient medium must provide a carbon source such as sucrose and also inorganic salts, vitamins, amino acids and growth regulators like auxins, cytokinins etc.

By application of these methods it is possible to achieve propagation of a large number of plants in very short durations. This method of producing thousands of plants through tissue culture is called micropropagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are some clones. Many important food plants like tomato, banana, apple, etc., have been produced on commercial scale using this method.