The function notation \( f(n) = n^2 \) defines a sequence where each term is the square of its position \( n \).
For \( n = 1 \), \( f(1) = 1^2 = 1 \)
For \( n = 2 \), \( f(2) = 2^2 = 4 \)
For \( n = 3 \), \( f(3) = 3^2 = 9 \)
For \( n = 4 \), \( f(4) = 4^2 = 16 \)
For \( n = 5 \), \( f(5) = 5^2 = 25 \)
From the options you provided, the sequence that matches with \( f(n) = n^2 \) is:
\( a_n = 1, 4, 9, 16, 25, \ldots \)
So the correct response is: \( a_n = 1, 4, 9, 16, 25, \ldots \)