ANSWER
[tex]D.\text{ }387[/tex]
EXPLANATION
The sum of an arithmetic series is given by:
[tex]S_n=\frac{n}{2}(2a+(n-1)d)[/tex]
where a = first term
d = common difference
n = number of terms
From the question, we see that n is 9, the first term is 19, and the common difference is:
[tex]\begin{gathered} d=25-19 \\ \\ d=6 \end{gathered}[/tex]
Therefore, the sum of the first 9 terms is:
[tex]\begin{gathered} S_9=\frac{9}{2}(2(19)+(9-1)*6) \\ \\ S_9=\frac{9}{2}(38+48)=\frac{9}{2}*86 \\ \\ S_9=387 \end{gathered}[/tex]
The answer is option D.
