In the world’s broad field of battle,In the bivouac of life,

The image of life as a “field of battle” and a “bivouac” (a temporary camp) presents life as a struggle that calls for courage and effort. So the best choice is “Life is an eternal struggle.” The lines do not say that life is hopeless or not worth living; they encourage people to face its challenges bravely.

AI-written and checked against the verified answer.