You are working on a jewelry store that sells rings. Each ring allows an adjustment in size. The customer specifies finger size in inches and the merchant physically adjusts the stocked ring to the required size.
How is this represented in Magento?

You have configured an event observer to watch the checkout_submit_all_after event using this XML:

What is the required class definition for the event observer?

What is a valid use case for an aroundplugin?

You added a plugin declaration to MyCompany/MyModule/etc/di.xml:

What will be the effect of this declaration?

How do you set the custom block MyCompany\MyModule\Block\A as a child for the block named product.info using layout XML?