Final answer:
Soldiers are neither running in terror nor ignoring the falling artillery shells, but are engaging in battle with a mix of determination and resignation. Vivid literary depictions and historical texts illustrate soldiers' practical and resilient responses to the dangers of trench warfare.
Step-by-step explanation:
The way soldiers are responding to the shells dropping around them as they move through the lines can be inferred from various pieces of textual evidence. Firstly, from Siegfried Sassoon's poem "Counter-Attack," it's clear that soldiers are not running in terror but engaging in the battle with a mix of determination and resignation. The poem's vivid imagery depicts them firing back in the midst of chaos, despite being occasionally overwhelmed by the sensory overload of battle. Secondly, the reference to Sun Tzu's principles suggests that when soldiers have no refuge or are in desperate situations, they will fight with resilience ("Soldiers when in desperate straits lose the sense of fear... they will fight hard."). Lastly, the depiction of soldiers wondering about enemy activity and then being surprised by artillery shells suggests that while soldiers may be initially distracted or pondering, they quickly adopt a practical approach towards the imminent danger ("... And then, of course, they started with five-nines">). Thus, the third response option, that soldiers are ignoring the falling shells, also seems inaccurate. The soldiers are neither running in terror nor ignoring the threat, but are engaging with the enemy, being fully aware of the danger represented by the artillery shells and machine-gun fire, in a grim acceptance of the circumstances of trench warfare.