**Explanation:**

The correct answer is option **b) Land**.

In ancient India, kings often rewarded Brahmanas with grants of land. This practice was based on the principles of dharma and the social hierarchy of the time.

**1. Importance of Brahmanas:**
Brahmanas were considered the highest caste in the varna system and were responsible for performing religious rituals and ceremonies. They were regarded as the custodians of sacred knowledge and were highly respected in society.

**2. Role of Kings:**
Kings held a significant position in the social and political structure of ancient India. They were responsible for maintaining order, protecting their subjects, and upholding dharma. Kings were also expected to patronize Brahmanas and support religious and cultural activities.

**3. Rewards for Brahmanas:**
To show their appreciation and respect for the Brahmanas, kings often rewarded them with grants of land. These land grants were known as "brahmadeya" and were given as a form of royal favor and recognition. The land provided a means for the Brahmanas to sustain themselves and their families.

**4. Significance of Land Grants:**
Land was a valuable resource in ancient India as it provided a source of livelihood and sustenance. The land grants bestowed upon Brahmanas were typically tax-free and hereditary, ensuring long-term support for the recipients. These grants allowed Brahmanas to cultivate the land, collect revenue, and utilize the resources as per their needs.

**5. Purpose of Land Grants:**
The purpose behind these land grants was to promote the well-being of Brahmanas and their continued participation in religious and cultural activities. By providing them with a stable source of income and social status, the kings aimed to ensure the performance of rituals, ceremonies, and other religious duties.

**6. Role in Social Hierarchy:**
The land grants to Brahmanas reinforced the social hierarchy of ancient India. They solidified the Brahmanas' position as the highest caste and maintained their influence and authority in society. This practice also helped to legitimize the power of kings by aligning themselves with the religious elite.

In conclusion, kings often rewarded Brahmanas with grants of land as a means of expressing their respect and support for the religious and cultural activities performed by the Brahmanas. These land grants provided the Brahmanas with a stable source of income and social status, ensuring their continued participation in society.