Context: Martha, an eighth grade student and the protagonist of Marta Salinas' story 'The Scholarship Jacket', asks her grandpa for fifteen dollars to pay for the scholarship jacket.
The grandpa asks Martha, 'what does a scholarship jacket mean?'
Martha replies, 'It means you've earned it by having the highest grades for eight years and that's why they're giving it to you'.
Questions: Why did Martha use the Second Person pronouns instead of the First Person ones in her reply?
Is there any technical term (rhetorical device) for this kind of usage?