We're looking at lots of these positions because it's so important to become visually sensitive to enemy pieces on the same line. There are several here on the seventh rank, but more critical is the alignment of Black’s queen and rook in the corner—the same kernel as in the last problem. White has several ways to put an attacker on that diagonal with his queen, but of course that’s no good since Black just plays QxQ. White needs to attack with his bishop from a protected square to prevent Black’s queen from biting back. Bd5 accomplishes the mission. So you think: 1. Bd5, Qc8; 2. BxR, QxB, and White wins the exchange. Good, but now look for better. After Black moves his queen to c8, White can play the check Qe4+; once Black moves his king, White can take Black's rook with impunity because his bishop now has the queen's protection.