$\text{P+Q}$ means $\text{P}$ is the brother of $\text{Q}; \; \text{P-Q}$ means $\text{P}$ is the mother of $\text{Q}$ and $\text{P} \times \text{Q}$ means $\text{P}$ is the sister of $\text{Q}.$ Which of the following means $\text{M}$ is the maternal uncle of $\text{R}$ ?
- $\text{M – R + K}$
- $\text{M + K - R}$
- $\text{M + K} \times$ $\text{R}$
- $\text{M + R + K}$