Comprehensive and Detailed Step by Step Explanation:

Premature distributions from an Individual Retirement Account (IRA) before age 59½ are subject to a10% penalty tax, in addition to regular income tax, unless an exception applies.

10% (B):Correct. This is the standard penalty for early withdrawals under IRS regulations.

5% (A):Too low and not applicable to IRA penalties.

20% (C):Refers to mandatory withholding for some plan distributions, not the penalty rate.

50% (D):Applies only to missed Required Minimum Distributions (RMDs), not early withdrawals.

Exceptions to the 10% penalty:

First-time homebuyers (up to $10,000).

Qualified education expenses.

Medical expenses exceeding a certain percentage of adjusted gross income (AGI).