Final answer:
Warranty expense is not a permanent difference as it is deductible in different periods for tax and accounting purposes; it reverses over time, unlike the other listed items which are permanent differences.
Step-by-step explanation:
The item that is not considered a permanent difference is Warranty expense (d). Permanent differences are differences between tax and financial income that are not reversible. A permanent difference does not reverse in the future.
For example, Interest received on municipal bonds (a) is generally exempt from federal income taxes, and thus represents a permanent difference. Fines from violating the law (b) are not deductible for tax purposes, thus also a permanent difference. Premiums paid for life insurance (c) where a company is the beneficiary are not deductible for tax purposes, so that is another example of a permanent difference.
Whereas, warranty expenses (d) are deductible in different periods for tax and accounting purposes and are thus a temporary difference, not a permanent one.