The correct answer is $\boxed{\text{D}}$.
Statement 1: Some tapes are discs.
Statement 2: Some discs are cassettes.
Statement 3: Some cassettes are songs.
Conclusion 1: Some songs are discs.
This conclusion does not follow. Just because some tapes are discs and some discs are cassettes, it does not follow that some songs are discs. For example, all squares are rectangles, but not all rectangles are squares.
Conclusion 2: Some cassettes are tapes.
This conclusion does follow. If some tapes are discs and some discs are cassettes, then some cassettes must be tapes.
Conclusion 3: Some songs are tapes.
This conclusion does follow. If some tapes are discs and some discs are cassettes, and some cassettes are songs, then some songs must be tapes.
Conclusion 4: No song is a disc.
This conclusion does not follow. Just because some tapes are discs and some discs are cassettes, it does not follow that no song is a disc. For example, all squares are rectangles, but there are rectangles that are not squares.
Therefore, only conclusion 3 and either conclusion 2 or conclusion 4 follow.