What could be a result of improper adjustment of a manual transmission?

Improper adjustment of a manual transmission can lead to the transmission popping out of gear. This occurs when the linkage that connects the gear shifter to the transmission isn't correctly aligned, which can prevent the gears from engaging fully or holding their position. When the gears are not fully engaged due to misalignment, there is insufficient force to keep them seated, causing the transmission to become disengaged and thus pop out of gear unexpectedly.

The other options present outcomes that wouldn't typically result from poor adjustment of a manual transmission. Improved gear shifting and increased acceleration would imply that the system is functioning optimally, while transmission fluid leaks might indicate issues with seals or gaskets rather than the adjustment itself.