6.34 If it is known that $\lg 8=0.9031$, and $\lg 9=0.9542$, then the logarithm that cannot be uniquely determined without a logarithm table is
(A) $\lg 17$.
(B) $\lg \frac{5}{4}$.
(C) $\lg 15$.
(D) $\lg 600$.
(E) $\lg 4$.
(2nd American High School Mathematics Examination, 1951)