In a certain taxon of insects, some have $17$ chromosomes and the others have $18$ chromosomes. The $17$ and $18$ chromosome-bearing organisms are

The correct option is B Males and females, respectively
The sex-determination in insects is of XO-XX type. The males have XO sex chromosome, that means there is only sex chromosome in males apart from the autosomes. The females have XX sex chromosomes, that means there are two sex chromosomes apart from the autosomes. There are 16 autosomes in both the males and females. Males have total of 17 chromosomes (16+1 sex chromosome). Females have total of 18 chromosomes (16+2 sex chromosomes).

Hence, the correct answer is 'Males and Females, respectively'.