Answer: A. 9,978
Based on the power, move the decimal point that many spaces to the right. (E.g., If it's 4.2 × 10^3, then move the decimal three spaces to the right, and you'd get 4200.)
2.167 × 10^4 = 21670
1.1 × 10^6 = 1100000
2.468 × 10^5 = 246800
Out of all the numbers mentioned in the question, 9,978 is the only one that's less than 2.167 × 10^4 = 21670.