The options for this question are:
A) having good judgment
B) Honorable
C) Sorrowful
D) having a damaged reputation
Answer: D) having a damaged reputation.
Explanation: context clues are hints that the writer gives to help the readers understand a word or a phrase in a sentence or paragraph. In the given sentence we can know that the meaning of the word "discredited" is "having a damaged reputation" because the writer gives us the context clues "lying" and "humiliation." So we can infer that after being caught lying, the witness's reputation was damaged.