Write a correct answer to the given question based on its associated fact. Make sure that your answer is contained in the associated fact. Don't be creative and introduce any new word that is not mentioned in the associated fact! Remember that the associated fact has been rearranged to form the question. So, the correct answer words must lie within the associated fact. The correct answer can be a word, phrase, or even a sentence.

Fact: Vertebrates are all chordates that have a spinal column. 
Question: What do all vertebrates have that invertebrates don't?
a spinal column.

Fact: mold spore has a negative impact on survival. 
Question: What do mold spores have a negative impact on?
survival.

Fact: Hydrogen bonds cause H2O molecules to expand when frozen. 
Question: What bonds cause H2O to expand when freezing?

Hydrogen.