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A
One with a pH of 14
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B
One formulated to stay close to the natural pH of hair and skin (about 4.5–5.5)
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C
One with no pH
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D
One that is strongly alkaline
Why this is the answer
A 'pH-balanced' product is one formulated to stay close to the natural slightly acidic pH of hair and skin, roughly 4.5 to 5.5. Keeping a product in this range helps maintain the skin's protective acid mantle and keeps the hair cuticle smooth and compact, reducing damage. Many shampoos and skin products are marketed as pH-balanced for this reason. Understanding what pH-balanced means — and why staying near the natural pH matters — connects the chemistry and skin/hair-science content of the exam.
Source: Scientific Concepts — pH-Balanced Products