Answer:
The correct answer is letter "A", "B", and "C": Please; At your request; Thank you.
Explanation:
Stale or trite phrases are used in business but they interfere with clarity and directness because they tend to be redundant. These phrases unnecessarily increment the length of a message. Examples of stale phrases are: "Enclosed please find..." or "With reference to...".
"Please", "At your request", and "Thank you" are straight-clear phrases.