The value that has been fulfilled by A in this scenario is integrity.

**Explanation:**

1. **Integrity**: Integrity refers to the quality of being honest, having strong moral principles, and adhering to ethical standards. In this case, A displayed integrity by declining to receive the commission offered by the supplier and requesting a reduction in the purchase price instead.

2. **Partnership and Authorization**: A and B are partners, and A has been authorized to buy goods for the firm. As an authorized partner, A has the responsibility to act in the best interest of the partnership and make decisions that align with the agreed-upon principles and goals.

3. **Order Placement**: A placed an order of Rs. 10,00,000 with a supplier. This implies that A has the authority to make purchasing decisions on behalf of the firm.

4. **Commission Offer**: The supplier offered a 15% commission to A. This commission could have been seen as an opportunity for personal gain, as A could have accepted the commission and benefited financially.

5. **Declining the Commission**: A declined to receive the commission offered by the supplier. This decision shows that A prioritizes the interests of the firm over personal financial gain.

6. **Request for Reduced Purchase Price**: Instead of accepting the commission, A requested the supplier to reduce the purchase price by 15%. This demonstrates A's commitment to obtaining the best possible deal for the firm, even if it means forgoing personal benefits.

7. **Supplier Agreement**: The supplier agreed to reduce the purchase price as requested by A. This indicates that the supplier recognized the fairness of A's request and was willing to accommodate it.

By declining the commission and requesting a reduction in the purchase price, A has displayed integrity by prioritizing the firm's interests over personal gain. A's actions demonstrate a sense of responsibility and ethical decision-making, which are essential values in business partnerships.