Write the expression as a single function of $\alpha$.
\[
\cos \left(0^{\circ}+\alpha\right)
\]
Choose the correct answer below.
A. $-\cos \alpha$
B. $\cos \alpha$
C. $-\sin \alpha$
D. $\sin \alpha$

Step 1 ：Write the expression as a single function of \(\alpha\).

Step 2 ：\[\cos \left(0^{\circ}+\alpha\right)\]

Step 3 ：Choose the correct answer below.

Step 4 ：A. \(-\cos \alpha\)

Step 5 ：B. \(\cos \alpha\)

Step 6 ：C. \(-\sin \alpha\)

Step 7 ：D. \(\sin \alpha\)

Step 8 ：The expression \(\cos \left(0^{\circ}+\alpha\right)\) can be simplified using the trigonometric identity for the cosine of a sum of two angles, which is \(\cos(a+b) = \cos a \cos b - \sin a \sin b\). In this case, \(a = 0^{\circ}\) and \(b = \alpha\). Since \(\cos 0^{\circ} = 1\) and \(\sin 0^{\circ} = 0\), the expression simplifies to \(\cos \alpha\). Therefore, the correct answer is B. \(\cos \alpha\).

Step 9 ：Final Answer: The correct answer is B. \(\boxed{\cos \alpha}\).