The Z-score is calculated using the formula:
\[
z = \frac{X - \mu}{\sigma}
\]
Substituting the values:
\[
z = \frac{1.96 - 0}{1} = 1.96
\]
Thus, the Z-score is \( z = 1.96 \).
The Standard Error \( SE \) is calculated as follows:
\[
SE = \frac{\sigma}{\sqrt{n}} = \frac{15}{\sqrt{30}} \approx 2.7386
\]
The test statistic \( Z_{test} \) is calculated using the formula:
\[
Z_{test} = \frac{\bar{x} - \mu_0}{SE}
\]
Substituting the values:
\[
Z_{test} = \frac{105 - 100}{2.7386} \approx 1.8257
\]
For a two-tailed test, the P-value is calculated as:
\[
P = 2 \times (1 - T(|z|)) \approx 0.0679
\]
In the z-test using rejection region(s), the test statistic \( Z_{test} \) is compared with critical values. In contrast, the z-test using a P-value compares the P-value with the level of significance \( \alpha \).
The correct answer is:
\(\boxed{C}\)