Step 1: Understanding the Concept:
This is a factual question asking to identify the scientist who is considered the pioneer and "father" of paleobotany (the study of fossil plants) in India.
Step 2: Detailed Explanation:
Professor Birbal Sahni (1891–1949) was a renowned Indian paleobotanist.
He made significant contributions to the study of the fossil flora of the Indian subcontinent, which helped in understanding the paleogeography and geology of the region.
He founded the Institute of Palaeobotany in Lucknow in 1946, which was later renamed the Birbal Sahni Institute of Palaeosciences in his honor.
Due to his pioneering work and immense contributions, he is universally acclaimed as the "Father of Indian Paleobotany."
The other names are incorrect. Bhishma Sahni was a famous Hindi writer, and Balraj Sahni was a celebrated film actor; both were brothers of Birbal Sahni.
Step 3: Final Answer:
Professor Birbal Sahni is known as the father of Indian paleobotany.