Which of the following is true to implement the Buy/Sell Transactions and Brokers classes and the association between them in the preceding UML class diagram in a database?

1-The primary key of Brokers is a foreign key in Buy/Sell Transactions.

2-The primary key of Buy/Sell Transactions is a foreign key in Brokers.

3-The association between Brokers and Buy/Sell Transactions is implemented as a linking table.

4-Both "The primary key of Brokers is a foreign key in Buy/Sell Transactions" and "The primary key of Buy/Sell Transactions is a foreign key in Brokers" are true.

5-None of these is true.