Explanation

Starting from Bikaner in the Thar desert, the first vegetation encountered is desert scrub. Moving south-east through Rajasthan and Madhya Pradesh, the route passes through tropical thorny forests. Further east through Chhattisgarh and interior Odisha it crosses moist deciduous forests. Near Konark on the Odisha coast, mangrove vegetation appears, as in the Bhitarkanika region. The correct sequence is therefore desert, tropical thorny, moist deciduous, mangrove.