Option c is right .
A balance of both auxin and cytokinin will often produce an unorganized growth of cells, or callus, but the morphology of the outgrowth will depend on the plant species as well as the medium composition. So, in tissue culture roots can be induced by lower concentration of cytokinin and higher concentration of auxins.

Inducing Roots in Tissue Culture

In tissue culture, the growth of roots can be induced through the manipulation of plant hormones, specifically cytokinins and auxins. The correct answer to the question is option 'C', which suggests that a lower concentration of cytokinin and a higher concentration of auxins are required to induce root formation in tissue culture. Let's understand the reasons behind this answer in detail.

1. Role of Auxins and Cytokinins
- Auxins are plant hormones that promote cell elongation, differentiation, and root development. They play a crucial role in initiating root primordia formation.
- Cytokinins, on the other hand, are responsible for promoting cell division and shoot development. They inhibit root formation and promote shoot growth.

2. Root Induction Mechanism
- In tissue culture, the manipulation of auxins and cytokinins can direct the growth and development of plant tissues.
- To induce root formation, the concentration of auxins needs to be higher than cytokinins. This is because a lower concentration of cytokinins encourages the development of root primordia.
- Higher levels of auxins in relation to cytokinins promote the initiation of root meristem and subsequent root growth.

3. Inhibition of Shoot Growth
- By using a lower concentration of cytokinins, shoot growth is inhibited, allowing the plant tissue to focus on root development. This is important because cytokinins primarily promote shoot growth and inhibit root development.

4. Optimal Hormone Concentrations
- The optimal balance between auxins and cytokinins for root induction depends on the plant species and tissue type.
- However, in general, a lower concentration of cytokinins (e.g., kinetin, zeatin) and a higher concentration of auxins (e.g., indole-3-acetic acid, naphthaleneacetic acid) are effective in promoting root formation in tissue culture.

In conclusion, to induce root formation in tissue culture, the correct combination of plant hormones is crucial. By using a lower concentration of cytokinins and a higher concentration of auxins, the growth of roots can be stimulated, while shoot growth is inhibited. This hormone manipulation allows researchers to efficiently propagate plants in vitro and study root development in a controlled environment.