In which sentence is all PUNCTUATION correct?

In which of the following sentences is all PUNCTUATION correct?

The soldiers returned from the war……they had fought bravely for many months.

When I was 25 years old, I ---------- lift 30 kilograms with one hand.

The woman .............. gave the presentation teaches at our university.

I've been looking for Professor Brown. ........ 30 minutes. Do you know where he is?