Consider the relation scheme $R = (E, F, G, H, I, J, K, L, M, N)$ and the set of functional dependencies $\{\{E, F\} \rightarrow \{G\}, \{F\} \rightarrow \{I, J\}, \{E, H\} \rightarrow \{K, L\}, \{K\} \rightarrow \{M\}, \{L\} \rightarrow \{N\}\}$ on $R$. What is the key for $R$?

To determine the candidate key for relation schema $R(E, F, G, H, I, J, K, L, M, N)$:

1. Identify essential attributes: Look at the right-hand side of all given FDs:

   • $RHS = \{G, I, J, K, L, M, N\}$

   • Attributes missing from the RHS of all FDs are $\{E, F, H\}$. These attributes must be part of every candidate key since they cannot be derived from any other attribute.

2. Compute the attribute closure of $\{E, F, H\}$:

   • $\{E, F, H\}^+ = \{E, F, H\}$

   • Using $\{E, F\} \rightarrow \{G\}$, add $G$: $\{E, F, G, H\}$

   • Using $\{F\} \rightarrow \{I, J\}$, add $I, J$: $\{E, F, G, H, I, J\}$

   • Using $\{E, H\} \rightarrow \{K, L\}$, add $K, L$: $\{E, F, G, H, I, J, K, L\}$

   • Using $\{K\} \rightarrow \{M\}$, add $M$: $\{E, F, G, H, I, J, K, L, M\}$

   • Using $\{L\} \rightarrow \{N\}$, add $N$: $\{E, F, G, H, I, J, K, L, M, N\} = R$

Since $\{E, F, H\}^+$ contains all attributes of $R$ and no proper subset can be a key, $\{E, F, H\}$ is the candidate key for $R$.

Hence, option (B) is correct.