A student titrates 25.00 mL of a monoprotic acid solution with 0.100 M NaOH. The indicator changes color after 24.60 mL of NaOH have been added. Later analysis shows that the true equivalence volume is 24.30 mL. What is the percent error in the acid concentration calculated from the endpoint data?
(a) 2.5 \%
(b) 0.60 \%
(c) 1.2 \%
(d) 0.30 \%