The political importance of the Great Compromise and the Three-Fifths Compromise was to "reinforce the unity of the New England merchants and the southern planters."
This is evident in the fact that the Great Compromise and the Three-Fifths Compromise solved the issue of slave population and representation in Congress among the American States.
The Great Compromise solved the issue of differences in States' population towards their representation in Congress.
On the other hand, Three-Fifths Compromise solved the issue of slaves being counted as part of the population.
It was concluded that a 3 out of 5 slaves population would be counted.
Hence, in this case, the correct answer is option C "reinforce the unity of the New England merchants and the southern planters."
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