Step 1: Identify the rule.
When converting an assertive sentence containing "rarely" to interrogative form, we use an affirmative question. For third-person singular present tense, the auxiliary "does" is used.
Step 2: Apply the transformation.
"He rarely speaks" becomes "Does he rarely speak?" -- the main verb loses its "-s" ending when "does" is introduced as the auxiliary verb.
Step 3: Eliminate wrong options.
Options 1, 2, and 3 either use wrong word order or retain the "-s" on "speaks." Option 4 correctly places "Does" first and uses the base form "speak." \[ \boxed{\text{Does he rarely speak in English to his friend?}} \]