Why Is It Considered Preferable to Buy Disability Insurance on an After-Tax

Why is it considered preferable to buy disability insurance on an after-tax basis?

A) You are not allowed to purchase disability insurance on a pretax basis.
B) If you purchase disability insurance on an after-tax basis and later are disabled, the income benefit you receive while disabled will be tax-free.
C) Disability insurance is so inexpensive that a pretax purchase is an administrative burden.
D) The tax rate on benefits is less than the tax rate on regular earnings.