A long, straight wire carrying a steady current \(I\) lies in the same plane as a right-triangular loop. The side of the loop of height \(h\) is parallel to the wire at a distance \(a\) from it. The base of the loop has length \(b\) and extends perpendicularly away from the wire, so that the vertex opposite the vertical side is at a distance \(a + b\) from the wire. Which of the following expressions is equal to the magnetic flux \(\Phi_B\) through the triangular loop?