Final answer:
The sentence 'I wanted to ask Ian what was up; he seemed sad' has the most friendly and approachable tone due to its informal language and expression of concern for someone else's emotional state.
Step-by-step explanation:
The sentence that most clearly has a friendly, approachable tone is D. I wanted to ask Ian what was up; he seemed sad. This sentence uses informal language and expresses a genuine concern for someone else's well-being, which conveys a sense of friendliness and approachability. The use of 'wanted to ask' and 'seemed sad' indicates a personal interest in the individual's emotional state, making the tone of the sentence personable and concerned.
Comparatively, the other sentences are either too formal or lack the warm, personal touch that makes them feel less friendly and approachable. For example, sentence C is very formal, while sentences A and B, although positive, do not explicitly convey a friendly interaction in the same way that sentence D does.