PLEASE HELP! How to setup a drop down selection

Could someone please tell me what selector to use and how to set it up? I have a site that has a drop down list. I have to scrap all the different choices in the drop down menu and get product information on each size.

Sitemap: https://www.marinedepot.com/red-sea-no3-po4-x-algae-management-supplement

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Something like this:
{"_id":"marinedepot","startUrl":["https://www.marinedepot.com/red-sea-no3-po4-x-algae-management-supplement"],"selectors":[{"id":"Clcik sizes","type":"SelectorElementClick","parentSelectors":["_root"],"selector":".row div.col-sm-5","multiple":true,"delay":"2200","clickElementSelector":"div > div[class^='form-group'] > select > option:nth-child(n+2)","clickType":"clickOnce","discardInitialElements":"discard-when-click-element-exists","clickElementUniquenessType":"uniqueText"},{"id":"Product name","type":"SelectorText","parentSelectors":["Clcik sizes"],"selector":"span[itemprop='name']","multiple":false,"regex":"","delay":0},{"id":"Price","type":"SelectorText","parentSelectors":["Clcik sizes"],"selector":"span[itemprop='price']","multiple":false,"regex":"","delay":0},{"id":"Item number","type":"SelectorText","parentSelectors":["Clcik sizes"],"selector":"p.form-control-static","multiple":false,"regex":"","delay":0}]}

Please use this URL: https://www.marinedepot.com/red-sea-no3-po4-x-algae-management-supplement

I very much appreciate your reply (no one else has replied) I have tried to figure out what you are directing me to do for a month and can't get it to work. Could you please, please resend you direction in a step by step method? I am not good with computers and want to update my product from my supplier.