The query concerns festivals connected to agriculture. An analysis of each festival follows:
- Bihu: Observed in Assam, Bihu is intrinsically linked to agriculture, coinciding with the Assamese New Year and the commencement of the harvest period.
- Baisakhi: Primarily celebrated in Punjab, this festival is associated with the harvesting of Rabi crops.
- Holi: While Holi signifies the arrival of spring, it is a festival of colors and not directly tied to agricultural activities.
- Pongal: Celebrated predominantly in Tamil Nadu, Pongal is a thanksgiving festival honoring the Sun God for a bountiful harvest.
Based on this examination, Bihu, Baisakhi, and Pongal are the festivals specifically related to agriculture.
Consequently, the correct selections are (A), (B), and (D) exclusively.