MCQ
For every integer $n$, let $a_n$ and $b_n$ be real numbers. Let function $f: I R \rightarrow$ $IR$ be given by $f(x)=\left\{\begin{array}{ll}a_n+\sin \pi x, & \text { for } x \in[2 n, 2 n+1] \\ b_n+\cos \pi x, & \text { for } x \in(2 n-1,2 n)\end{array}\right.$, for all integers $n$.
If $f$ is continuous, then which of the following hold$(s)$ for all $n$ ?
$(A)$ $a_{n-1}-b_{n-1}=0$ $(B)$ $a_n-b_n=1$ $(C)$ $a_n-b_{n+1}=1$ $(D)$ $a_{n-1}-b_n=-1$
- ✓$(B,D)$
- B$(B,C)$
- C$(A,D)$
- D$(C,D)$