When using a two-point calibration method to correct pH on a pH meter, if the test solution is acidic, the appropriate standard buffer solution should be

A、Standard buffer solutions (25℃) at pH 6.864 and 9.182.;
B、Standard buffer solution at pH 4.003 (25℃).;
C、Standard buffer solutions (25℃) at pH 6.864 and 4.003.;
D、Standard buffer solution at pH 6.864 (25℃).