$$\begin{gathered} Emma Jane made an error proving that 2 3 1 n is divisible by 8 \\ (for n t1), u\sin g mathematical induction. Part of her proof is shown \\ below. \\ Step 2: Assume the result true for n=k \\ 3^{2k}-1=8P where P is an integer \\ Hence 3^{2k}=8P+1 \\ Step 3: To prove the result is true for n=k+1 \\ RTP:3^{2(k+1)}-1=8Q where Q is an integer. Line 1 \\ LHS=3^{2k+2}-1 Line 2 \\ =3^{2k}\times 3^2-1 \\ =(8P+1)\times 3^2-1 (u\sin g the assumption) Line 3 \\ =72P+1-1 Line 4 \\ =8\left(9P\right) \\ =8Q \\ =RHS \\ In which line did Emma Jane make an error? \\ A) Line 1 \\ B) Line 2 \\ C) Line 3 \\ D) Line 4 \end{gathered}$$