Why did the western front barely move throughout world war 1?

The Western Front barely moved throughout World War I because the major method of warfare during World War I was called trench warfare. Trench warfare was essentially digging into positions and defending them from attackers. There were major advancements made in weaponry such as machine guns at this time, but there were not similar advancements in the mobility of weaponry. Therefore, forces simply dug in and defended positions without making much movement at all. 

A,b,c is the answer to the question