Which of the following salts give acidic aqueous solutions?

$(1)KN{O}_3$

$(2)KC{H}_{3\text{C}\text{O}\text{O}}$

$(3)N{H}_{4}N{O}_3$

$(4)$ RbI

$(5)(N{H}_4{)}_{2}S{O}_4$

$(6)BaC{l}_2$

$(7)$ NaCN

$(8)KN{O}_2$

a$.1,4,8$

b$.3,5$

c$.$ only $3$

d$.2,3,5$