Answer: C. A mix of functions and concatenation of 10 account fields and 10 opportunity fields.

A formula field can be used to create a new field that is a combination of existing fields, functions, and calculations. This means that an app builder should be able to configure a formula field to do all of the following:

A hyperlink to the parent account of the parent opportunity. This can be done by using the HYPERLINK function to create a link to the account record.
A Rich text area field that uses HTML to bold certain characters. This can be done by using the FORMAT function to apply the BOLD formatting to specific characters in the text.
A mix of functions and concatenation of 10 account fields and 10 opportunity fields. This can be done by using the CONCATENATE function to combine the values of 10 account fields and 10 opportunity fields.
**A combination of the opportunitys text and a description fields.** This can be done by using theCONCATENATE` function to combine the values of the opportunity's text field and the description field.
Note that formula fields cannot be used to create new data types, such as a Rich text area field. However, they can be used to create new fields that are a combination of existing data types....

I think it's B

D is correct

Nope it's it's C

nope, it is B actually

correct answer is D