The correct decreasing order of priority for the functional groups of organic compounds in the IUPAC system of nomenclature is

While writing IUPAC names, only one functional group is chosen as the principal (suffix-giving) group.

This choice is made with the help of the “seniority list” (priority order) fixed by IUPAC. Near the top of that list we find, in the exact order :

$$\text{(i) } -SO_3H \; (\text{sulfonic acid}) \; \gt $$ $$\text{(ii) } -COOH \; (\text{carboxylic acid}) \; \gt $$ $$\text{(iii) } -CONH_2 \; (\text{amide}) \; \gt $$ $$\text{(iv) } -CHO \; (\text{aldehyde})$$

The group that appears earlier in the list is given higher priority. Therefore the decreasing (highest → lowest) order of priority for the four groups asked in the question is

$$-SO_3H \; \gt \; -COOH \; \gt \; -CONH_2 \; \gt \; -CHO$$

This sequence corresponds to Option B.

Option B which is: $$-SO_3H, -COOH, -CONH_2, -CHO$$