Final answer:
Interest-only mortgage (B)
Step-by-step explanation:
The mortgage type that rarely exists in today's marketplace and is typically for a very short time period is the interest-only mortgage (B). An interest-only mortgage allows the borrower to only pay the interest on the loan for a specific period, typically between 5 to 10 years. After this period, the borrower must start paying both the principal and interest, leading to higher monthly payments.