One problem with the stock market right before the crash was that people were buying "on margin."

What does buying "on margin" mean?

Responses

A person buys stock one day and plan to sell it the next.
A person buys stock one day and plan to sell it the next.

A person buys stock in foreign countries.
A person buys stock in foreign countries.

A person buys stock in high-risk companies.
A person buys stock in high-risk companies.

A person borrows money to buy stock.

A person borrows money to buy stock.