The correct answer is option 'A': Harisena.

Introduction:
The court poet of Samudragupta, who composed the Prayaga Prashasti, also known as the Allahabad Pillar Inscription, was Harisena. Harisena was a highly respected poet and scholar during the reign of Samudragupta, who was one of the most illustrious rulers of the Gupta Empire in ancient India. The Prayaga Prashasti is considered one of the most important inscriptions of the Gupta period, providing valuable insights into the reign of Samudragupta and the achievements of his empire.

Harisena and his Work:

1. Harisena was a court poet:
- Harisena served as a court poet in the court of Samudragupta.
- As a court poet, he was responsible for composing poems and inscriptions that glorified the king and his achievements.

2. Composition of the Prayaga Prashasti:
- The Prayaga Prashasti is an inscription that was carved on the Allahabad Pillar, also known as the Ashoka Pillar.
- It was composed by Harisena to commemorate the military successes and conquests of Samudragupta.
- The inscription is written in Sanskrit and is considered a masterpiece of Gupta literature.

3. Description of Samudragupta's conquests:
- The Prayaga Prashasti provides a detailed account of Samudragupta's military campaigns and conquests.
- It describes his victories over various kingdoms and rulers, including those of Assam, Bengal, Nepal, and the Deccan region.
- The inscription also mentions the submission of several foreign kings and the tribute they paid to Samudragupta.

4. Praises for Samudragupta:
- Harisena's composition is filled with praises for Samudragupta, extolling his virtues, bravery, and military prowess.
- The inscription refers to Samudragupta as a great warrior and a righteous ruler who brought peace and prosperity to his empire.
- Harisena's poetic skills are evident in the way he portrays Samudragupta as a divine figure, comparing him to gods and celestial beings.

Conclusion:
In conclusion, Harisena, the court poet of Samudragupta, was responsible for composing the Prayaga Prashasti, also known as the Allahabad Pillar Inscription. This inscription, written in Sanskrit, glorified the military conquests and achievements of Samudragupta. Harisena's work provides valuable insights into the reign of Samudragupta and the Gupta Empire during the ancient period in India.