IUPAC naming Question

I feel kinda silly asking this question but can someone explain this?

For IUPAC numbering are we looking for the lowest sum of all numbers? Or are we looking for the lowest number for each group/highest priority?

I put the answer as B

I thought that the isopropyl has a higher priority so it would get the lower number

I feel kinda silly asking this question but can someone explain this?

For IUPAC numbering are we looking for the lowest sum of all numbers? Or are we looking for the lowest number for each group/highest priority?

I put the answer as B

I thought that the isopropyl has a higher priority so it would get the lower number