38. In the titration of a weak acid HA with 0.100 M NaOH the stoichiometric point is known to occur at a pH value of approximately 10. Which of the following indicator acids would be best to use to mark the endpoint of this titration?
(A) indicator A, 10-14
(B)indicator B,iTa= 10-11  
(C)indicator C,Ka= 10-8
(D)indicator D, Ka = 10-6
(E)noneof these