Question: How do you extract the values above the main diagonal from a square matrix named `Rmat`?

1. `Rmat[upper.tri(Rmat)]`
2. `upper.triangular(Rmat)`
3. `upper.tri(Rmat)`
4. `upper.diag(Rmat)`

Answer: The correct answer of the above question is Option A:`Rmat[upper.tri(Rmat)]`