John and Denise's joint return shows what amount of tax owed on the social security benefits?

When determining the tax owed on Social Security benefits on a joint return, it's important to consider how much of those benefits are subject to tax based on the couple's combined income. Typically, if a taxpayer's provisional income falls below a certain threshold, then none of their Social Security benefits are taxable. For joint filers, the threshold is generally set where up to 50% of benefits may be taxable for combined income between $32,000 and $44,000, and up to 85% for income exceeding $44,000.

In this scenario, if John and Denise's provisional income is below the threshold, it means that none of their Social Security benefits are taxable. This would lead to an amount of tax owed on the Social Security benefits being nil. Therefore, the correct answer is that there is no tax owed on the Social Security benefits, resulting in the selection of B.