The word UNDERLING is a valid English word that ends with the letters ‘ING’.
It means a subordinate or someone of lower rank or position.
While ‘UNDER’ is the prefix and ‘LING’ is a diminutive suffix, together they form ‘UNDERLING’, which is a standard English noun.
The other options—ABOVELING, BELOWLING, and OVERLING—are not standard or recognized English words.
Therefore, the only correct word among the options is UNDERLING, making option (A) correct.