Which of the following is a major principle upon which cell theory is based? a all cells form by free-cell formation. b all cells have dna. c all organisms are made of cells. d all cells are eukaryotic.

i believe it's c. the trait for large beaks will be passed on to future generations through natural selection.

since eventually smaller beaks would have to find another source of food or even eventually just die out from the lack of food.