Science task 175: A New Zealand Level 1 learner applies foundational knowledge to a familiar community context. What is [H⁺] when pH=4?

A. 1 × 10⁻5 mol L⁻¹ B. 4 mol L⁻¹ C. 1 × 10⁻4 mol L⁻¹ D. 1 × 10^4 mol L⁻¹