A punctuation question with a joining word tests whether the words on each side form full sentences. Split at the joining word and find who or what each side is about and what it does or is. Ask whether each side can stand alone. Two full sentences can meet at a period, a semicolon, or a comma paired with a joining word. A part that can't stand alone must stay attached instead, so don't punctuate by the pause you hear.
Hints
- Hint 1
Find who does what on each side of the blank, then test whether each side can stand alone.
- Hint 2
Check how the two parts are linked. What job does yet do, and which punctuation patterns can connect full sentences?
Step-by-step
Split and test the join
Step 1Test the first part
Many migratory birds rely tells us who we're talking about and what they do. Since the choices change punctuation around yet, let's split there to test the join. Does the first part stand alone? Adding navigate completes what the birds rely on the field to do, so the first part is a full sentence.
- Step 2
Test the second part
Can the words after the blank stand alone too? In scientists still do not fully understand, scientists tells us who, and do not fully understand tells us what they don't do. The rest says what they don't understand: how the birds sense the field. This part is also a full sentence, so we're joining two full sentences.
- Step 3
Apply the joining-word pattern
Yet means but, so it shows a contrast: birds rely on Earth’s magnetic field, while scientists still do not fully understand how birds sense it. A comma before the joining word correctly connects the full sentences, giving navigate, yet. Choice A.