Harishena was the court poet of:

Samudragupta

The correct answer is Option (3) → Samudragupta

The Prayaga Prashasti (also known as the Allahabad Pillar Inscription) composed in Sanskrit by Harishena, the court poet of Samudragupta, arguably the most powerful of the Gupta rulers (c. fourth century CE), is a case in point. The Prayaga Prashasti praises the Gupta ruler Samudragupta.