Step 1: Understand the question.
It asks where India's first farm university was built.
Step 2: Recall the place.
The first farm university opened in 1960 at Pantnagar. It was first named Uttar Pradesh Agricultural University and later became G. B. Pant University of Agriculture and Technology. Pantnagar then lay in Uttar Pradesh and is now in Uttarakhand.
Step 3: Choose the answer.
Pusa, New Delhi and Sabour are not the first one, so the right option is Pantnagar.
\[ \boxed{\text{Pantnagar}} \]