What makes a QSVT polynomial admissible?

Question: In standard Quantum Singular Value Transformation, why can we not simply choose any real polynomial p(x) and apply it to the singular values of a block-encoded matrix? A) Because QSVT works only for exactly linear polynomials B) Because the polynomial must satisfy structural constraints such as boundedness and parity conditions compatible with a unitary phase sequence C) Because QSVT can transform eigenvalues but not singular values D) Because the block-encoding normalization α must always equal one Correct: B Explanation: QSVT implements polynomial transformations through unitary signal-processing sequences. The target polynomial must be physically realizable inside a unitary construction, so boundedness and parity-type constraints matter. Arbitrary polynomials must usually be approximated by admissible ones. Topic: advanced quantum computing / QSVT / polynomial constraints