Decise the underlined part A, B, C or D that is not correct in standard English.

1. Because his argument was soconfused->confusing, few people understood it.
2. A famous musicianis going to->will go todirect the concert next week.
3. Scientistsmust->xhave to discover an alternative source of energy before oil runs out.
4. To enjoy an opera fully, the listener should be familiar with the story, particularly is the opera issinging->sungin a foreign language.
5. To have a stong body and stayhealthily->healthy, you should exercise regularly.

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