(1) Their average is divisible by 6 This means that the 4th number is divisible by 6; therefore, the first 3 terms and the last three terms are not divisible by 6. Only one term (4th term) is divisible).
(2) Their median is divisible by 12 This means that the 4th number is divisible by 12 (and 6); therefore, the first 3 terms and the last three terms are not divisible by 6. Only one term (4th term) is divisible).
(1) Their average is divisible by 6
This means that the 4th number is divisible by 6; therefore, the first 3 terms and the last three terms are not divisible by 6. Only one term (4th term) is divisible).
(2) Their median is divisible by 12
This means that the 4th number is divisible by 12 (and 6); therefore, the first 3 terms and the last three terms are not divisible by 6. Only one term (4th term) is divisible).
SUFFICIENT D.