What makes QSVT powerful but demanding?

Question: Why is QSVT considered both powerful and technically demanding? A) It avoids all ancilla qubits and requires no phase synthesis B) It works only for diagonal matrices, but diagonalization is easy on a quantum computer C) It replaces all polynomial approximations with exact arbitrary functions D) It can implement polynomial transformations of block-encoded singular values, but requires a suitable block encoding and carefully chosen phase factors Correct: D Explanation: QSVT is powerful because many linear-algebraic quantum algorithms can be expressed as polynomial transformations of singular values. The challenge is that the matrix must be represented appropriately, and the desired transformation must be encoded through valid polynomial and phase-sequence construction. Topic: advanced quantum computing / QSVT / block encoding