16. Given functions $f(x), g(x)(x \in \mathrm{R})$, let the solution set of the inequality $|f(x)|+|g(x)|<a (a>0)$ be $M$, and the solution set of the inequality $|f(x)+g(x)|<a (a>0)$ be $N$, then the relationship between the solution sets $M$ and $N$ is ( ).
A. $M \subseteq N$
B. $M=N$
C. $N \varsubsetneqq M$
D. $M \varsubsetneqq N$
1). A;



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