Traer in the preterite tense for third person singular has the -o ending, but traer is an irregular verb in that you must add a j when conjugating this person. Therefore the answer is "trajo."
If you have other problems like this, websites like spanishdict.com are good for checking your work, and creating a table for the verb ("yo traje, t<span>ú </span>trajiste") to figure it out. :)
Judiciously: Making a good judgement that makes sense
（高中/大學）二年級（學）生
(Gao Chong/ Da Xue) Er nian ji (xue) sheng
Answer:
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Explanation:
