What should an app builder be able to configure using a formula field?

universal containers has several new fields they requested for the opportunity product object.

What should an app builder be able to configure using a formula field?
A . A hyperlink to the parent account of the parent opportunity.
B . A mix of functions and concatenation of 10 account fields and 10 opportunity fields.
C . A combination of the opportunity`s text and a description fields.
D . A Rich text area field that uses HTML to bold certain characters

Answer: D