What type of life insurance could Julie purchase to pay off her $100,000 mortgage if she dies within the 30-year period?

B is the correct choice because decreasing term insurance is specifically designed to cover decreasing financial obligations over time, such as a mortgage. In this type of policy, the death benefit reduces in correspondence with the remaining balance on the mortgage, usually on a consistent schedule over the term of the policy. This aligns perfectly with Julie's need to ensure that her mortgage is paid off in the event of her death within the next 30 years.

Adjustable life insurance allows the policyholder to adjust premiums and death benefits, but it doesn't inherently link to decreasing debts. Increasing term insurance provides a death benefit that rises over time, which wouldn’t address the specific need of covering a decreasing mortgage balance. Modified life insurance typically combines features of term and whole life but doesn’t focus on reducing coverage like a decreasing term policy.