The correct option is D 987, 789
Given the digits 7, 8 and 9.
The smallest 3-digit number formed from these digits is got by placing the smallest of these digits (7) in the hundreds place, the second smallest number (8) in the tens place and the third digit (9) in the units place, thus giving us 789.
Similarly, the largest number from the given digits is got by placing the largest of these digits (9) in the hundreds place, the second largest number (8) in the tens place and the smallest number (7) in the units place, thus giving us 987.