Which of the following mixtures has the highest pH? (a) Equal volumes of 1.0 M HCl and 1.0 M NaOH (b) Equal volumes of 0.1 M HNO3 and 0.1 M KOH (c) Equal volumes of 0.1 M HCN and 0.1 M NaOH (d) Equal volumes of 0.1 M NaF and 0.1 M HCl