I … a song when I got my letter of promotion.

Analyze the question

The sentence is "I ........ a song when I got my letter of promotion." We need the phrasal verb that fits with "a song", meaning the person suddenly started singing out of joy.

Explain the concept

Phrasal verbs with "break":

• break into (something): to suddenly begin to do something, such as break into song, laughter, a run, applause.
• break out: to start suddenly (a war, fire, or disease), or to escape. It is not followed directly by an object like "a song". We say "a fight broke out", not "I broke out a song". (Informally, "break out a song" can appear in some English, but it is not standard in WASSCE usage.)
• break for: to head toward something, or to pause for something (e.g., "break for lunch"). It does not fit here.
• break in: to enter a place by force, or to interrupt. It does not fit here.

Step-by-step solution

1. The object is "a song", and the meaning is suddenly starting to sing because of happiness.
2. The standard expression for this is "break into song".
3. Substituting: "I broke into a song when I got my letter of promotion." This is natural and correct.
4. The other options do not form a meaningful or standard phrase with "a song".

Answer: A. broke into

Tip: Remember the pattern "break into + sudden action": break into song, break into laughter, break into tears, break into a run. Use "break out" for things like wars, fires, riots, and diseases, as in "Cholera broke out in the town."