Step 1: Common collocation.
The idiomatic phrase is “a high-pitched voice.” Predicate form: “his voice was high pitched.” Step 2: Eliminate distractors.
(B) Awkward; (C) grammatically wrong; (D) meaningless; (E) comparative but no context. Step 3: Conclude.
(A) is the only idiomatic, precise form.
\[
\boxed{\text{Option (A)}}
\]