Exam PL-400 topic 2 question 30 discussion

You are a Power App maker.
You are developing an app in a development environment. You create the following custom forms in the Account entity:
FormB contains a message that appears in the OnLoad function of the form.

✑ FormC contains a message that appears in the OnSave function of the form.
You add the forms to a solution and export the solution as managed. Importing the managed solution into the test environment produces an error indicating the solution is missing a component.
You need to identify the issue.
What is the cause of the import error?