Difficulty grasping Functional Dependency concepts with MySQL

Question

I can write queries fairly well, but basic Database Design concepts continue to frustrate me :/ I'm working through an old book to try and brush up on the material, but functional dependencies are really making my head spin. For instance, the following question:

Assume that Marcia keeps a table of data about her customers. Consider just the following part of that table: CUSTOMER(Phone, FirstName, LastName) Explain the conditions under which each of the following are true:

1. Phone --> (FirstName, LastName)
2. (Phone, FirstName) --> LastName
3. (Phone, LastName) --> First Name
4. (LastName, FirstName) --> Phone
5. Phone --> --> LastName
6. Phone --> --> FirstName
7. Phone --> --> (FirstName, LastName)

I don't even understand how to go about answering the question!..

Answer 1

I'm not an expert on Db design, but from what I understand:

And assuming that Phone is unique.

1. True. Because a Client's's FirstName and Last Name can be uniquely determined from their Phone

2. True.

3. True

4. False

The double narrow I dont know what it is mean