In Spanish, why are the present-tense verbs for TO COMPETE considered to be stem-changing verbs? A. Because, in some of them, when E is stressed, it is changed to IE B. Because, in some of them, when O is stressed, it is changed to UE C. Because, in some of them, when E is stressed, it is changed to I D. Because, in some situations, the first-person singular is irregular.