If several teeth break off a gear, which gear is likely to create noise?

When several teeth break off a gear in a manual transmission, the gear that is being engaged at that moment will typically create noise. In the case of the gears listed, second gear is especially prone to generating noise due to how it interacts with the other components in the transmission.

When a gear has missing teeth, it disrupts the smooth engagement with its mating gear. As the broken gear rotates, the remaining teeth may strike with increased force against the opposing gear, leading to a potential clattering or grinding sound. Second gear is often used during various driving conditions, and if it is engaged while the damage occurs, the sound produced would be more noticeable.

While first gear and reverse can also produce noise if they are engaged when gear damage occurs, second gear tends to be engaged more frequently in typical driving scenarios after the initial take-off, thus making any noise from it more prevalent. Choosing second gear reflects an understanding of gear usage frequency combined with the impact of mechanical failure, providing a strong reasoning for why this option is the best answer in the context provided.