The correct answer is option 'B' - Pratiharas.

The Pratiharas were a powerful dynasty that ruled over a large part of North India from the 8th to the 11th century. They were known for their strong military and administrative capabilities, and played a crucial role in defending India against the hostility of the Muslims during this period.

1. Rise of the Pratiharas:
The Pratiharas rose to power in the region of present-day Rajasthan and Madhya Pradesh, and their empire eventually extended from Gujarat in the west to Bihar in the east. They were initially vassals of the Gurjara-Pratihara Empire, but later established their own independent kingdom.

2. Strong Military:
The Pratiharas had a well-organized and powerful military force. They had a large cavalry, which was effective in warfare against the Muslim invaders who primarily relied on cavalry attacks. The Pratiharas also had a strong infantry and were known for their skilled archers.

3. Junaid of Sind:
Junaid was a prominent Muslim general who invaded India in the early 8th century. He attacked the kingdom of the Gurjara-Pratiharas, but was defeated by their king, Nagabhata II. This victory marked the beginning of the Pratiharas' defense against Muslim invasions.

4. Rashtrakutas and Ghaznavids:
The Rashtrakutas of Deccan and the Ghaznavids of Afghanistan were two other Muslim dynasties that posed a threat to India during this period. The Pratiharas successfully defended against their attacks as well. For example, in the 10th century, the Pratiharas under king Mihira Bhoja repelled the Rashtrakuta invasion.

5. Mahmud of Ghazni:
Mahmud of Ghazni was one of the most prominent Muslim invader who repeatedly attacked India in the 11th century. The Pratiharas, under the leadership of king Bhoja, put up a strong resistance against Mahmud's invasions. However, their empire eventually weakened due to internal conflicts and political instability, and Mahmud was able to capture and plunder many of their cities.

In conclusion, the Pratiharas stood as a fortification of India's defense against the hostility of the Muslims from the days of Junaid of Sind to Mahmud of Ghazni. Their strong military capabilities and strategic leadership played a crucial role in defending India against the Muslim invasions during this period.