What four-carbon compound is regenerated at the end of the krebs cycle? with what two-carbon compound does it combine at the start of the krebs cycle?

When one dna molecule is copied to make two dna molecules, the new dna contains a) 25% of the parent dna. b) 50% of the parent dna. c) 75% of the parent dna. d) 100% of the parent dna. e) none of the parent dna.