Uttararamacharita by____ is based on Valmiki’s Ramayana.

The correct option is Bhavabhuti.

Uttararamacharita (The Later Story of Rama) is a celebrated Sanskrit play in seven acts written by the 8th-century Sanskrit scholar and dramatist Bhavabhuti.
The play is based on the Uttara Kanda, the final section of Valmiki’s epic, the Ramayana. It details the later life of Rama, starting from his coronation, covering the exile of Sita, Rama's grief, and their eventual reunion.

Let's look at the other options to understand the context of each author:
- Bhasa: An early Sanskrit dramatist known for works like Swapnavasavadatta and Pratimanataka.
- Bharavi: A classical poet famous for the epic poem Kiratarjuniya, which is based on a story from the Mahabharata.
- Kalidasa: One of the greatest Sanskrit poets and playwrights, known for works like Abhijnanasakuntalam and the epic poem Raghuvamsha.