what would you say is the tone of this headline
"Call to lower blood-alcohol limit for drivers"
This could be interpreted in a variety of ways. So heres my spin on it - I would say that the tone is fervent as it is insinuating a "call" which is somewhat of a plea to say the last. Due to the nature, you could say it's "pleading" it sounds like the writer is insinuating 'enough is enough' it must be done. What does the rest of the article 'sound' like? It can be at times difficult to interrupt the tone solely based of the headline, so maybe explore the article to try and see what you can pick apart. Ask yourself is the tone quite frivolous in the article or assertive and authoritative?
The notion of 'calling' may be interrupted in a variety of ways so exploring how the text of the article is structured and presented may help you in determining the tone of the piece.