A projectile of mass \(m\) is launched horizontally with a constant initial speed \(v_0\) into a stationary wooden block of mass \(M\) suspended from the ceiling by a light string. The projectile becomes embedded in the block, causing the block-projectile system to swing upward to a maximum angle \(\theta\) relative to the vertical. Students repeat the trial with different string lengths \(L\) while keeping all other parameters constant, measuring the resulting maximum angle \(\theta\) for each length. Which of the following graphs will yield a straight line whose slope can be used to determine \(v_0\)?