Which of the following was not a Princely state in British India?

The correct answer is Option 3 - United Province

United Province was one of the British Indian provinces.

British India was divided into two entities: The British Indian Provinces (Punjab, United Province, Assam, etc.) and the Princely States (Hyderabad, Kashmir, Bhopal, Junagadh, Manipur, Travancore, etc.).
The British Indian Provinces were directly governed by the British government.
The Princely States were territories ruled by princes and enjoyed a degree of control over their internal affairs.
The Princely States accepted the British crown's paramountcy or suzerainty, recognizing British supremacy.
The Princely States constituted approximately one-third of the land area of British India.
About one out of four Indians lived under the rule of the Princely States.