The correct option is D A-2, B-3, C-1
Coimbatore, Chennai, Tiruvallur, Kancheepuram, Villupuram, Dharmapuri, Salem, Madurai, and Tirunelveli are the most populous districts in the state starting from the highest. Districts with a population of 30- 35 lakh are Tiruvannamalai, Cuddalore, Tiruchirapalli and Thanjavur. These come in regions of moderate population. Vellore, Dindigul, Virudhunagar, and Thoothukudi districts have a population of about 15 to 20 lakhs. The population of less than 15 lakh belongs to regions of the sparse population. Coastal districts Nagapattinam, Tiruvarur, Pudukottai, Ramanathapuram, and Sivagangai have a population less than 15 lakh. The northwestern district of Nilgiris has a population of less than 10 lakh and is the least populated district.