Which of the following trees are planted along the sewage pond for purifying waste water? 

Eucalyptus tree

The correct answer is option 1. Eucalyptus tree.

It has been suggested that we should plant “eucalyptus trees” all along the sewage ponds. This is due to the fact that eucalyptus trees quickly absorb all the excess wastewater from the sewage ponds and then transpire clean water vapor into the atmosphere. Eucalyptus trees aid in the quick purification of wastewater in this way.