Using quotation marks in fields

I’m trying to use a drop down menu field using quotation marks but obviously that affects the code. What would be the correct way to write this so I can use ” instead of inches.

This is what I am using:

[select* DepthOptions include_blank "6 inch Nominal" "8 inch Nominal" "10 inch Nominal" "Custom"]

I’d like to use this:

[select* DepthOptions include_blank "6" Nominal" "8" Nominal" "10" Nominal" "Custom"]