The correct answer is B) x = {5, 6, 7, 8, 9, ... }.
To see why, let's break down the inequality x < 5. This inequality means that x can be any number that is less than 5, but not including 5 itself. In other words, x can be any number in the open interval (-∞, 5).
The solution set for this inequality is any set of numbers that satisfies this condition. The set of numbers in option B) {5, 6, 7, 8, 9, ... } is the only set that satisfies this condition, since all of these numbers are less than 5.
Option A) {5, 4, 3, 2, 1, ... } includes 5, which is not a solution to the inequality x < 5.
Option C) {4, 3, 2, 1, ... } does not include any numbers greater than or equal to 5, so it does not satisfy the inequality x < 5.
Option D) {3, 4, 5, 6, 7, ... } includes 5, which is not a solution to the inequality x < 5.