Final answer:
The Tennessee Constitution of 1796 was unique in allowing all free men over 21 and who were landowners to vote, regardless of race, which contrasts with other states that either continued denying voting rights to free blacks or limited suffrage expansions to White males.
Step-by-step explanation:
The Tennessee Constitution of 1796 was unique in several ways, but based on historical context, the statement that best describes its uniqueness is that all free men, regardless of race, could vote if they were landowners and over 21 years of age (D). This was at a time when in other states following the Revolutionary period, the trend was to either continue denying the right to vote to free blacks like in Georgia, South Carolina, North Carolina, and Virginia or, like in Pennsylvania and New Hampshire, to lower or remove property requirements for White males.
The efforts in other states usually resulted in expanding the electorate to more White males, either through taxpayer suffrage or lowering property qualifications, but explicitly or effectively excluding non-whites. The other statements, such as the reference to a state supreme court (B and E) or the governor's veto power (C and F), are not uniquely descriptive of Tennessee's constitution as some states had similar provisions, like Pennsylvania's 1790 constitution which instituted a governor with veto power.