The correct answer is Option 1: a Persian script used in medieval India.

Nastaliq is a type of calligraphic script that originated in Persia (modern-day Iran) during the 14th century. It is characterized by its elegant and flowing style, which is especially suitable for writing Persian and Urdu languages. Nastaliq script was widely used in the medieval period and continued to be used in various regions, including India.

During the medieval era, India was under the influence of various Persianate Muslim dynasties, including the Delhi Sultanate and the Mughal Empire. These rulers patronized Persian culture, including literature, art, and calligraphy. As a result, the Nastaliq script gained popularity and became an important script used for writing Persian and Urdu languages in India.

Nastaliq script is known for its intricate design and curvilinear shapes, with letters connected to each other in a cursive manner. It is highly regarded as one of the most beautiful and artistic calligraphic scripts, and it continues to be used in traditional and contemporary contexts for poetry, manuscripts, and other artistic expressions in the Persian and Urdu languages.

While the other options provided in the question are not directly related to Nastaliq, let`s briefly discuss them for clarity:

Option 2: "a raga composed by Tansen"

Ragas are melodic frameworks in Indian classical music, and Tansen was a prominent musician in the court of Mughal Emperor Akbar. While Tansen composed numerous ragas, there is no specific mention or connection between Nastaliq and a raga composed by him.

Option 3: "a cess levied by the Mughal rulers"

Cess refers to a tax or levy imposed by the government. The Mughal rulers did impose various taxes and levies during their reign, but there is no known connection between Nastaliq and a specific cess imposed by them.

Option 4: "a manual of code of conduct for the Ulemas"

Ulemas are Islamic scholars, and manuals of code of conduct are indeed present in Islamic tradition. However, there is no known connection between Nastaliq and a specific manual of code of conduct for the Ulemas.

In conclusion, Nastaliq was a Persian script used in medieval India, particularly during the periods of Persianate Muslim rule, and it continues to be a revered and admired calligraphic style for Persian and Urdu languages.