Final answer:
The first speed gear in the transmission is locked to the counter shaft.
Step-by-step explanation:
In the transmission, the first speed gear is locked to the A) counter shaft. The counter shaft is responsible for transmitting power from the engine to the gearbox. It is connected to several gears, including the first speed gear. When power flows through the transmission in first gear, the first speed gear on the counter shaft is locked and rotates at a specific speed determined by the gear ratio.