Step 1: Understand the task.
We must arrange the grammatical cases labelled $K, L, M, N, O$ into their standard order as used in Hindi grammar.
Step 2: Recall the fixed sequence of cases.
The classical order of the eight relational cases runs Karta, Karm, Karan, Sampradan, Apadan, Sambandh, Adhikaran.
Step 3: Place each label on this ladder.
Karan $(L)$ sits at position 3, Sampradan $(M)$ at 4, Apadan $(N)$ at 5, Sambandh $(O)$ at 6, and Adhikaran $(K)$ at 7.
Step 4: Read off the numerical order.
Sorting these positions gives $3 \rightarrow 4 \rightarrow 5 \rightarrow 6 \rightarrow 7$.
Step 5: Substitute the labels back.
This becomes $L \rightarrow M \rightarrow N \rightarrow O \rightarrow K$.
Step 6: Confirm with the options.
This clean ascending chain matches option B exactly.
\[ \boxed{\text{B. } L \rightarrow M \rightarrow N \rightarrow O \rightarrow K} \]