Which tax forms are commonly used to report capital gains?

The correct answer focuses on Schedule D and Form 8949 because these are the specific forms required for reporting capital gains in the United States. Schedule D is used to report the overall net capital gain or loss from transactions reported on Form 8949, where individual sales of capital assets are detailed.

Form 8949 allows taxpayers to report each transaction involving the sale of stocks, bonds, and other capital assets, including the date of acquisition, date of sale, proceeds from the sale, cost basis, and the gain or loss realized. After detailing the transactions on Form 8949, the totals are summarized on Schedule D, which ultimately informs the taxpayer's overall tax liability.

This distinction is crucial since other forms listed, like Form 1040 and Schedule C, are primarily for reporting ordinary income and self-employment income rather than capital gains. Similarly, Form 1065 and Schedule K-1 deal with partnership income, while Form W-2 and Form 1099 focus on reporting wages and miscellaneous income, respectively. Therefore, B is the answer that correctly identifies the appropriate forms for reporting capital gains.