Somaclones are:

The correct answer is Option (1) → Plants genetically identical to the original plant from which they are grown.

Option (1) Plants genetically identical to the original plant from which they are grown. — Correct. In tissue culture, a small part of a plant (an explant) is grown in a nutrient medium under sterile conditions. Its cells divide only by mitosis, so every new plant has the same genes as the parent. Thousands of such plants can be made in a short time.

Option (2) Plants genetically dissimilar to the original plant from which they are grown. — Incorrect. This is the reverse. No gametes fuse and no meiosis takes place in tissue culture, so no new combination of genes can form. Genetically different plants come from sexual reproduction or from somatic hybridisation.

Option (3) Plants grown from only shoots in the test tube. — Incorrect. The explant can be any part of a plant, not only a shoot. A whole plant can grow from any cell or explant; this capacity is called totipotency.

Option (4) Genetically engineered plants. — Incorrect. A genetically engineered (GM) plant has a foreign gene put into it, as in Bt cotton. A somaclone carries no new gene; it is a copy of its parent.

NCERT Extract:
Biotechnological Applications in Agriculture – “… 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 micro-propagation. Each of these plants will be genetically identical to the original plant from which they were grown, i.e., they are somaclones.”