Question

HELP ME!!

Which sentence is correct?

The scientist said there is only one thing: to be done to save our river, "Stop polluting the groundwater with fertilizers."

The scientist said: there is only one thing to be done to save our river "Stop polluting the groundwater with fertilizers."

The scientist said there is only one thing to be done: to save our river "Stop polluting the groundwater with fertilizers."

The scientist said there is only one thing to be done to save our river: "Stop polluting the groundwater with fertilizers."

Answer 1

I believe the first one is correct

Answer 2

I think I say the first one is right