Nucleotides are a base pair and they fit together because their shape allows them to bond. The A-T pair frames two hydrogen bonds. G-C forms 3. As the strands bond they hold the Base Pairs of DNA together
It takes the food you eat, breaks it up into small pieces, and turns it into energy
There are more than simply 4 biological compounds in the human body. I suppose to categorise, the question is hinting towards the molecules like Carbohydrates ( Poly and mono saccharides ) Proteins ( Polypeptides Made of amino acids) and Fats. There is also water, but I'm hesitant to class that as a biological compound, as it's not organic.
The statement that most correctly describes surrogacy is C, fertilizing sperm and egg in a lab and implanting it into another woman's uterus. This is the definition of gestational surrogacy, which involves In Vitro Fertilization. Gestational surrogacy also means the carrier is not genetically related to the baby, only the father.