Choose the correct meaning of the given idiom from the options below:

"To fight tooth and nail"

To fight heroically and fiercely

The correct meaning of the idiom "to fight tooth and nail" is to fight heroically and fiercely. The idiom comes from the literal meaning of fighting with one's teeth and nails, which is to fight with all of one's strength and determination. In the same way, when someone "fights tooth and nail," they are fighting with all of their might and are not giving up easily.

The other options are not as accurate. Making an effort to win means that someone is trying to achieve something, but it does not necessarily mean that they are fighting heroically or fiercely. To fight in a cowardly manner means that someone is fighting in a way that is not brave or honorable. To fight alone means that someone is fighting without any help from others.