Evaluate log8 log16

The angle subtended by an arc at the center of a circle is twice the angle subtended by the same arc at any point on the remaining part of the circumference. Here, arc AC subtends $\angle AOC$ at the center and $\angle ABC$ at the circumference.

Given $\angle ABC = 30^\circ$.

This corresponds to option D.

The final answer is $\boxed{\text{D. } 60^\circ}$.

The common base for 8 and 16 is 2.

Upon reviewing the options, $\frac{4}{3}$ is not present. Let's re-evaluate the interpretation. If the question intended to be $\log_{16} 8$, let's check that.

Re-evaluation based on options: If the question was $\log_{16} 8$:

This value matches option D. Given the options, it is highly probable that the question intended to be $\log_{16} 8$.

The final answer is $\boxed{\text{D. } \frac{3}{4}}$.

We need a number $a$ such that $2a \equiv 1 \pmod{7}$.
By testing values:
$2 \times 1 = 2 \pmod{7}$
$2 \times 2 = 4 \pmod{7}$
$2 \times 3 = 6 \pmod{7}$
$2 \times 4 = 8 \equiv 1 \pmod{7}$
So, the inverse of $2 \pmod{7}$ is 4.

Since $8 \equiv 1 \pmod{7}$ and $12 \equiv 5 \pmod{7}$:

The congruence $y \equiv 5 \pmod{7}$ means $y$ can be $5, 12, 19, \dots$. The least whole number value is 5.
This corresponds to option A.

The final answer is $\boxed{\text{A. } 5}$.