Correct Answer: L B P O B N B O

Solution : Given:
P _ _ O N _ L B _ N P L _ O _ P L _ _ N

To fill the series we have to divide the series – P _ _ O N / _ L B _ N / P L _ O _ / P L _ _ N
Let's check each option –
First option: L B P O B N B O; P L B O N / P L B O N / P L B O N / P L B O N (PLBON is repeated in the series)
Second option: L B P B O N B O; P L B O N / P L B B N / P L O O N / P L B O N (No repeated pattern has been found)
Third option: L P B O B N N O; P L P O N / B L B O N / P L B O N / P L N O N (No repeated pattern has been found)
Fourth option: L B P O B B N O; P L B O N / P L B O N / P L B O B / P L N O N (No repeated pattern has been found)

So, the series becomes→P L B O N P L B O N P L B O N P L B O N. Hence, the first option is correct.