Question 165·Hard·Boundaries
Over the past decade, Dr. Mendes has investigated coral bleaching in Belize, Guatemala, and Honduras; charted sea turtle migration near Cape Verde, São Tomé, and Príncipe; _____ microplastic accumulation along beaches in Bali, Indonesia.
Which choice completes the text so that it conforms to the conventions of Standard English?
For punctuation-boundaries questions, first identify whether the sentence is listing parallel items or joining clauses. If items contain internal commas, use semicolons to separate the major items and avoid stacking punctuation. Choose the option that preserves the established pattern and adds only what’s needed—often just a conjunction.
Hints
Spot the list pattern
Notice the sentence is listing several actions, and each action includes its own commas (lists of places). What punctuation is used to separate the big items in that list?
Look at what comes right before the blank
The word right before the blank is a semicolon. That semicolon already creates a boundary—so be careful about adding more punctuation immediately after it.
Avoid stacking punctuation
A coordinating conjunction like and usually doesn’t take a semicolon, colon, or comma immediately after it in this kind of list. Choose the option that keeps the third action parallel to the first two.
Step-by-step Explanation
Identify the structure of the sentence
The sentence presents three actions performed by Dr. Mendes. Each action contains internal commas (place lists like “Belize, Guatemala, and Honduras”), so the writer correctly uses semicolons to separate the major items in the series.
Decide what belongs after the semicolon
Because a semicolon already separates the second and third items (right before the blank), the blank should begin the third item in the series. To keep the series parallel and avoid stacking punctuation, you should not add an extra semicolon, colon, or comma immediately after the conjunction.
Choose the option that avoids unnecessary punctuation
Options that add punctuation right after and ("and; analyzed", "and: analyzed", "and, analyzed") create incorrect or unnecessary punctuation in a semicolon-separated series. The only choice that correctly introduces the final item without extra punctuation is "and analyzed".