Sailors once relied on the stars for navigation ______ now most ships use GPS systems for accurate positioning.
Which choice completes the text so that it conforms to the conventions of Standard English?
- A
—but
- B
but
- Ccheck_circle
, but
- D
, but,
Explanation
Comma plus "but" correctly joins two independent contrasting clauses. " but" is a run-on; ", but," is over-punctuated; "—but" is nonstandard.