What is the mode of dissolution of the firm followed by G, K and B?

The correct option is Dissolution by Agreement.

Step-by-Step Explanation:
A partnership firm can be dissolved in various ways under partnership law. Let's look at the legal provisions and why "Dissolution by Agreement" is the correct mode here:
1. Dissolution by Agreement (Section 40): A partnership firm can be dissolved at any time with the consent of all the partners. Alternatively, it can be dissolved in accordance with the terms of a pre-existing contract or agreement made between the partners. Since partners G, K, and B can mutually decide to end their business relationship through mutual consent or as per their partnership deed, this mode is referred to as "Dissolution by Agreement".
2. Compulsory Dissolution (Section 41): This occurs automatically under circumstances such as the insolvency of all partners (or all but one) or when the business of the firm becomes unlawful.
3. On the happening of certain contingencies (Section 42): Subject to a contract between the partners, a firm may be dissolved upon specific events like the expiry of a fixed term, completion of a specific adventure/undertaking, death of a partner, or adjudication of a partner as insolvent.
4. Dissolution by Notice (Section 43): If the partnership is "at will," any partner can dissolve the firm by giving a written notice of dissolution to all other partners.
Therefore, when partners G, K, and B decide to wind up their firm through mutual consent or according to their contract, it falls under Dissolution by Agreement.