Why did most of the combat on the Western Front in World War 1 take place in a relative small area

B. The armies became immobile because of trench warfare

Explanation:

Trench Warfare had stopped the mobilization and progress on both sides for over two years. The Constant stalemate of attacking waves of men to gain little land progress.

the answer is actually b.   as habitats are destroyed, animals and plants may become extinct.   , according to edge nuity