Which of the statements is sufficient to answer the question?

Question:

Find the value of n.

Statements:

1) \(A\; = \;\left[ {\begin{array}{*{20}{c}} n&1\\ 0&-1 \end{array}} \right]\)

2) \(B\; = \;\left[ {\begin{array}{*{20}{c}} 1&-1\\ 0&1 \end{array}} \right]\)

3) A + B = O, where O is a null matrix of 2 × 2