If your question literally says, “The Virginia Plan called for representative __________,” the only way to fill in the blank would be “government.” However, this does not make much sense because all of the plans presented at the Constitutional Convention called for representative government. No one really thought that there was any other way to structure a government. Therefore, I wonder if the question really reads something like “The Virginia Plan called for representatives…” or “called for representation…” In both cases, the answer would need to be more than one word.
In both cases, the answer should be something like “to be based on population or taxes.” This was one of the major features of the Virginia Plan. According to that plan, each state’s representation in Congress was to be proportional to either its population or the amount of tax money that it contributed to the national government. Either way, the idea was that the larger states should have more representatives than the smaller states. Since Virginia was a large state, it made sense that Virginians would like this idea.
The main feature of the Virginia Plan was the way in which it would have apportioned representation in Congress. Therefore, I think that this statement should read something like “the Virginia Plan called for representatives in Congress to be apportioned based on the sizes of the states.”