For a train to come to a safe halt, it must always pass a signal showing a yellow light before reaching a signal showing a red light. The driver applies the brake at the yellow light, causing the train to decelerate uniformly until it stops exactly at the red light. The separation between the red and yellow lights is $x$. What is the least possible distance between the lights if the train speed is increased by $20\%$, while the trains’ deceleration remains unchanged?
- A$1.20x$
- B$1.25x$
- C$1.44x$
- D$1.56x$