Final answer:
The greatest exponent in the function describing an arithmetic sequence with a common difference of 6a is (b) 0, because the sequence increases by a linear rate, not an exponential one.
Step-by-step explanation:
If the common difference in an arithmetic sequence is 6a, then to determine the greatest exponent in the function describing this sequence, we should consider the general form of an arithmetic sequence's nth term:
n-th term = first term + (n - 1) × common difference
This is a linear equation, and thus it has no exponents for n. The common difference, 6a, is a coefficient. Therefore, the answer to the question, "What is the greatest exponent in the function describing this sequence?" is (b) 0. No exponents appear in the formula, as the sequence increases by a constant amount, not an exponential rate.