Represents an option on a selling plan group that's available in the drop-down list in the storefront.
Individual selling plans contribute their options to the associated selling plan group. For example, a selling plan group might have an option called `option1: Delivery every`. One selling plan in that group could contribute `option1: 2 weeks` with the pricing for that option, and another selling plan could contribute `option1: 4 weeks`, with different pricing.