In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.
A recent census of waterbirds conducted as a part of Asian Waterbird Census (1)______ an increase in their population in Najafgarh Jheel this year. The census also showed a (2)______ in the number of threatened species. Last year, the number of waterbird species were thirty one which climbed to fifty- four this year, while the threatened variety (3)______ from four to six in the same duration. The region also saw a healthy monsoon in 2019, which would have (4)______ impacted the quality of habitat, making it (5)______ to more birds.
Select the most appropriate option for blank number 4.