Step 1: Use the word sitcom:
The question says sitcom with real-life issues. That points to a family comedy that added serious episodes, not an adult cartoon.
Step 2: Recall known episodes:
Diff'rent Strokes ran a two-part story in which a shop owner tried to harm the boys, and another episode with drug use featuring a famous guest. These are its best known episodes.
Step 3: Why not the others:
Taxi followed cab drivers in a garage and Cheers followed regulars in a Boston bar. Their stories were about jobs and love, with no famous episodes on abuse or drugs.
Step 4: Rule out the rest:
Taxi and Cheers were light workplace and bar comedies. South Park is animated satire and does not match the idea of a gentle family sitcom with a special episode.
Final Answer:
Option 1, Diff'rent Strokes, is the show that used its special episodes for these serious topics.
\[ \boxed{\text{Diff'rent Strokes}} \]