4. (8 points) A 12-term arithmetic sequence, with a common difference of 2, and the sum of the first 8 terms equals the sum of the last 4 terms. What is the second term of this sequence?
A. 7
B. 9
C. 11
D. 13
【Solution】Solution: According to the problem, the sum of the last 4 terms equals the sum of the first 8 terms, which indicates that this is an increasing sequence,
$$
\left(a_{1}+a_{8}\right) \times 8 \div 2=\left(a_{9}+a_{12}\right) \times 4 \div 2 \text {, }
$$

Since $a_{8}=a_{1}+14, a_{9}=a_{1}+16, a_{12}=a_{1}+22$,
substituting these values gives $\left(a_{1}+a_{1}+14\right) \times 8 \div 2=\left(a_{1}+16+a_{1}+22\right) \times 4 \div 2$,
solving this yields $a_{1}=5$,
thus $a_{2}=a_{1}+2=7$.
Therefore, the answer is: $A$.