Quiz Yourself: Querying Multiple Tables

Consider the following query:

CREATE TABLE Customers
(
    Id INT PRIMARY KEY IDENTITY(1, 1),
    Name NVARCHAR(100) NOT NULL,
    Email NVARCHAR(100) NOT NULL
);

CREATE TABLE Items
(
    Id INT PRIMARY KEY IDENTITY(1, 1),
    Title NVARCHAR(100) NOT NULL,
    Description NVARCHAR(100) NULL,
    Price NUMERIC(18, 2)
);

CREATE TABLE Orders
(
    ItemId INT REFERENCES Items (Id),
    CustomerId INT REFERENCES Customers (Id),
    OrderDate DATETIME NOT NULL,
    PRIMARY KEY (ItemId, CustomerId, OrderDate)
);

(Select all that apply.) Which option(s) are foreign keys?