Question

Which of these sentences is the best example of a call to action?
a.
But Washington believes action now could help avert future disasters, such as coastlines lost to rising sea levels and extreme shrinkage of the polar ice caps.
c.
Otherwise, the vampire-like gadgets continue to suck electricity from the lines.
b.
You can even help slow global warming by taking shorter showers.
d.
all of these

Answer 1

A call to action is basically telling the reader what to do.

The only thing here that tells us what to do is taking shorter showers.
So I would say b is the call to action.