Which sentence contains a tense-choice error under the stated premise?
Sam had not planned to help, but on seeing the boxes he says, 'Here, let me — I am going to carry them.'✓Respuesta correcta
The tailor confirmed my Friday noon fitting, so I am seeing her then.
The pavement is already shining with ice; someone is going to slip.
I think the home team will recover after the break.
Explicación
Sam explicitly says that he had not planned to help and makes the offer on the spot, so the spontaneous response requires will. Be going to presents an intention formed before speaking, which contradicts "here, let me" and the stated absence of a prior plan.