The potential energy of a system increases if work is done

The correct option is B on the system against a conservative force.

Potential energy $U$ for a system is defined as:
$W_{\text{int}}=-\Delta U=-(U_f-U_i)...\left(1\right)$
${\int }_i^f\overrightarrow{F}\cdot \overrightarrow{dr}=-(U_f-U_i)...\left(2\right)$
$\Rightarrow$Where $\overrightarrow{F}$ is an internal conservative force, and $W_{\text{int}}$ is work done by the internal conservative force.
$\Rightarrow$ If $U$ increases then $U_f>U_i$ , or the term $-(U_f-U_i)$ will be $-ve$.

$\Rightarrow$ $W_{\text{int}}$ will become $-ve$
Hence we can say that if the work is done by the system then the internal energy of the body will increases.