Calculate the determinant of the given 3 x 3 matrix.

The determinant of a matrix $\begin{vmatrix} a & b & c \\ d & e & f \\ g & h & i \end{vmatrix}$ can be found by expanding along the first column: $a(ei - fh) - d(bi - ch) + g(bf - ce)$.
For the given matrix $\begin{vmatrix} 0 & 3 & 2 \\ 1 & 7 & 8 \\ 0 & 5 & 4 \end{vmatrix}$, we expand along the first column:

The correct option is A.

The final answer is $\boxed{\text{A. -2}}$.

25.

The interior angle of the regular polygon is given as $135^\circ$.
The sum of an interior angle and its corresponding exterior angle is $180^\circ$.

The sum of the exterior angles of any polygon is $360^\circ$. For a regular polygon with $n$ sides, all exterior angles are equal.

The correct option is A.

The final answer is $\boxed{\text{A. 8}}$.

26.

Given that $KL \parallel NM$ and $LN$ is a transversal, the alternate interior angles are equal.
Therefore, $\angle KLN = \angle LNM$.
Given $\angle KLN = 54^\circ$, so $\angle LNM = 54^\circ$.

Given that $LN$ bisects $\angle KNM$, it means $LN$ divides $\angle KNM$ into two equal angles.
So, $\angle KNL = \angle LNM$.
Since $\angle LNM = 54^\circ$, then $\angle KNL = 54^\circ$.

The sum of angles in a triangle is $180^\circ$. In $\triangle KMN$:

Given $\angle MKN = 35^\circ$ and we found $\angle KNM = 108^\circ$.

The final answer is $\boxed{37^\circ}$.