You are trying to determine why a product is not appearing in a category. What table does Magento on the frontend to locate the relationship between a category and its products?

Your module adds a new controller class which will return a JSON response.
What will be the return type of the execute method?

You are building CLI that use the console to create a customer account with our custom command, Adding a new command to CLI is based on passing on the argument from the XML level to the class. Dependency Injection comes in handy here. you create the file app/code/Mycompany/Customer/etc/di.xml with the following content: <type name="---------------------"> </type> What is the correct in below?

In a code review of a merchant's site you have discovered that there are multiple observers for the checkout_submit_all_after event. After closer inspection, you notice one of these observers is relying on the others being executed before it is called.
What risk does this pose, and how can it be mitigated?

You are making some major adjustments to a core Magento class (ClassA). These adjustments are only necessary when utilized from a specific Magento class (ClassB). You have created MyClass that contains the needed customizations.
Keeping upgradeability in mind, how do you configure di.xml to make the substitution happen?