A punctuation question with a title and a name tests whether the name is essential or extra. Read the words before the name and ask does the title already say which person? A name that identifies the person takes no commas, while a name that adds extra information takes a pair in the middle of a sentence. Then find the person’s main verb, because a lone comma can’t separate it from the person’s title and name.
Hints
- Hint 1
Look at the words before the blank. Do they make the title refer to only one person, or does the name need to say which person?
- Hint 2
Cross out the name and read the sentence with the title alone. Does that title still work as the person who argued?
Step-by-step
Test whether the name is needed
Step 1Find the person who argued
The words argued that the maria’s smoother surfaces result put the speaker’s main verb right after the blank. The choices repeat the same title and name, so we’re deciding where commas belong. Who argued? The title and Dr. Celeste Wu form the subject, the person who argued, so we need to decide whether the name identifies the person or adds extra information.
- Step 2
Test the title without the name
Do the words before the name already pick out one geologist? The word planetary tells us the field, but nothing before the title limits it to one person. There’s also no a or one to let the title stand alone. If we cross out Dr. Celeste Wu, we’d get planetary geologist argued, which doesn’t work because the singular title has no word such as a or the in front of it. So the name is essential: it says which geologist.
- Step 3
Apply the comma rule
An essential name takes no commas, while an extra name in the middle of a sentence needs a full pair. The version with a comma before the name opens a pair it never closes, and the version with a comma after the name separates the subject from argued. The version with commas at both ends wrongly treats the name as extra. Use geologist Dr. Celeste Wu, which joins the title to its identifying name and leaves the subject attached to its verb. Choice D.