A. pleased B. erased C. increased D. amused

Let's analyze the pronunciation of each word: 1. pleased: plizd - The main stress is not marked with "ˈ" because it's a single syllable word, and the stress is on the only syllable. 2. erased: ɪˈreɪst - The main stress is on the second syllable (re). 3. increased: ˈɪnkrist - The main stress is on the first syllable (in). 4. amused: əmˈjuzd - The main stress is on the second syllable (muse). Now, let's answer the question: 5. The word that has the main stress on the first syllable is **increased**. Therefore, the correct answer is C. increased.