Given a scientific question, generate a correct answer to it.

[EX Q]: What is light that has only a single wavelength called?
[EX A]: monochromatic

[EX Q]: Gravitational force on a large scale dominates interactions between large objects because it is always what?
[EX A]: attractive

[EX Q]: What kind of weather change do la nina years usually bring?
[EX A]:
drought