Which shows a perfect square trinomial?

A perfect square trinomial has the form a² + 2ab + b² or a² − 2ab + b². In choice B, 16x² = (4x)² and 9y² = (3y)², while the middle term 24xy equals 2(4x)(3y). Therefore, B is (4x + 3y)², a perfect square trinomial.

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