Concept:The writer's choice of words, or diction, builds the emotional mood of a passage.
Explanation:Words like "shocked stupor" and "blank vacancy" show that Grooby is mentally paralysed.
Phrases such as "unable to move" and "sweat that collected in his eyebrows" stress his complete physical immobility.
The simile "like a fly that dared not alight" suggests restless fear and confusion.
Also, "the air was actually burning gas" creates a heavy, suffocating atmosphere around him.
The tractor is seen "dwindling" and "melting into a glittering muddle," which reinforces his passive, lost condition.
These deliberate word choices point to powerlessness rather than hope, anger, or indifference.
Answer:B. helplessness