D. Catalyst
A catalyst is a reason for an event to occur.
Answer:passed
Explanation:
The new seedlings carrying the disease passed it to the established trees in the grove
I think it is A. Teenagers are an enjoyable and necessary part of our society.
Answer:
Library Collections. the published works and other documents collected by libraries for public use and made accessible through a system of catalogs and card files; also, one of the main divisions of library science.
Explanation: