Final answer:
Trench warfare led to a stalemate on the Western Front in World War I due to the fixed and fortified trench systems which neither side could bypass, resulting in prolonged, indecisive battles.
Step-by-step explanation:
Trench warfare caused a stalemate on the Western Front during World War I, making answer choice c, 'stalemate on the western front,' the correct response to the student's question. Though initially, trenches were improvised for immediate protection, they evolved into extensive fortified networks. With entrenched positions extending from the English Channel to the Swiss border, neither side could maneuver around the other's trenches effectively due to the introduction of new military technology and the vast armies. This inability to outflank the enemy led to a complete deadlock, characterized by long, drawn-out battles with heavy casualties, such as the Battle of Verdun.
On the Eastern Front, the situation was different. Russian troops, despite early successes, were hampered by inadequate resources and logistical issues, leading to a much more mobile and dynamic conflict. They were often outmaneuvered and defeated by German forces. Hence, option d, 'troop movement on the eastern front,' is not the direct result of trench warfare but rather a consequence of different circumstances on the Eastern Front.
The student's question regarding the impact of trench warfare clearly points to the static nature and stagnation caused by trench systems on the Western Front during World War I, rather than the defeats of France or Russia or troop movements on the Eastern Front.