I think spring that is usually when grow flowers come out after being dormant for the winter birds chirp
The correct answer is C.
In the summer of 1927, President Calvin Coolidge participated in the formal dedication of the massive stone monument known as Mount Rushmore, which was completed 14 years later." Hope this helps.
Even though you didn't give us the fragment with the comma slice, it isn't really necessary here as we can answer just based on these 4 options here. All options apart from the second one are correct - only the second option doesn't fix the mistake of the comma splice, whereas the other options do but connecting the sentences properly.
