Which is the FOURTH sentence of the paragraph?

d c e a b INTRODUCTION – Problem concern An assessment by the Wildlife Institute of India states that tigers in at least 26 reserves face the destructive impact of roads and traffic. STEPS to follow to address the problem The National Tiger Conservation Authority should insist on modification of existing roads to provide crossings for animals at locations identified in various studies. More stringent steps: A more robust approach would be to realign the roads away from all such landscapes. Users can be asked to pay a small price for the protection of vital environmental features, and more areas for nature tourism can also raise revenues. What will be achieved by these steps: This would ensure that tigers and other animals are not isolated, and can disperse strong genetic traits to other populations.