Final answer:
The base of the exponential term (−3)⁷ is −3, which is the number being raised to the power of seven. (Option B).
Step-by-step explanation:
The question asks what the base of the exponential term (−3)⁷ is.
In an exponential expression, the base is the number that is being raised to a power. Here, the number being raised to the seventh power is −3.
The exponent, in this case, is the number 7, which indicates the number of times the base, −3, is multiplied by itself.
Therefore, the correct answer is B. −3.