Collocation: A collocation is a pair or group of words that are habitually juxtaposed (used together) to sound natural to native speakers.
Context: The sentence starts with "I was running late," which implies that the person has very little time.
Why 'A' is correct: In English, the most natural way to describe a very fast wash when you are in a hurry is a "quick shower."
Why other options are incorrect: * B) luxurious: Implies high quality and comfort, which usually takes more time.
C) relaxed: Implies being calm and unhurried, which contradicts "running late."
D) long: Directly contradicts the fact that the speaker was "running late."