'required'

-- HikaShop version -- : 2.6.4
-- Joomla version -- : 3.6.4
-- PHP version -- : 5.6.27
-- Browser(s) name and version -- : Chrome 54.0.2840.87

Each product has 3 sizes. Each size has a different price.
I can create variants or options to achieve this.
But variants or options can't be made 'required'. Correct?

I know custom fields can be made 'required' but custom fields can't set the price in the cart. Correct?

If the choice is between three prices
Select
Small
Medium
Large
How can I make sure the buyer doesn't leave it as 'select'?

But if the existing variant is "select" then the buyer might leave it there and not select a size. True?

Yes. That works. Thank you.