We must make all-out effort/s to tackle the pollution problem.

[Tan Elaine]

We must make all-out efforts to tackle the pollution problem.
We must make all-out effort to tackle the pollution problem.

Which is the correct sentence?

Thanks.

 

[jutfrank]

all-out efforts or an all-out effort

 

[GoesStation]

I much prefer an​ all-out effort.