Since it's declarative, it ends with a period. We should add some commas as well.
<em>S</em>chool began on a cold<em>,</em> <em>S</em>eptember morning<em>.
</em>
That should work.
Answer:
A. Extent of the emotional investment in sports.
The first sentence uses 'in greeting' redundancy, as 'to bow' means to greet someone in a very polite, formal way.
"A tiny white diamond sparkled on her finger" technically has an error since there should be a comma after "tiny" although this is becoming more common usage.