Introduction:
Firuz Tughlaq was the third ruler of the Tughlaq dynasty in India, reigning from 1351 to 1388. He was known for his religious policies and crackdown on various sects and religious groups during his rule.

Explanation:
The correct answer is option 'D' - All of the above. Firuz Tughlaq prosecuted not only the Shias but also the Mahdis and the Karmathians, along with the Islamic Shias.

Firuz Tughlaq's Prosecution:
Under Firuz Tughlaq's rule, there was a significant crackdown on religious groups that were considered deviant or heretical. Let's discuss each of the mentioned groups:

1. Shias:
Firuz Tughlaq prosecuted the Shias, who were a minority sect within Islam. He implemented strict measures against them and their religious practices. As a part of his persecution, their religious books were publicly burnt, aiming to suppress their influence and beliefs.

2. Mahdis:
The Mahdis were a religious group that emerged during Firuz Tughlaq's reign. They claimed to be the messianic figures of Islam and gained a significant following. However, Firuz Tughlaq considered them to be a threat to his authority and prosecuted them as well.

3. Karmathians:
The Karmathians were a sect within Islam that originated during the 9th century. They held distinctive beliefs and practices, which often clashed with the mainstream Sunni orthodoxy. Firuz Tughlaq targeted and prosecuted the Karmathians, considering them to be a deviation from the accepted Islamic teachings.

4. Islamic Shias:
Apart from prosecuting the Shias, Firuz Tughlaq also targeted the Islamic Shias in general. This indicates that he had a broader policy of suppressing any sect or group that did not conform to his interpretation of Islam.

Conclusion:
In conclusion, Firuz Tughlaq's reign was marked by the prosecution and suppression of various religious groups, including the Shias, Mahdis, Karmathians, and Islamic Shias in general. His strict measures aimed to establish his authority and maintain Sunni orthodoxy as the dominant form of Islam during his rule. Therefore, the correct answer is option 'D' - All of the above.