What are the standards for choosing the target trees for the New York City's plan?
A.
The trees can break the stereotype of New York as skyscrapers and sidewalks.
B.
The trees can be easily noticed by the tourists passing in horse-drawn carriages.
C.
The trees are at least 100 years old and can serve as a name card of this city.
D.
The trees are hardier species and apparently attractive.