Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Tay-Sachs disease is a recessive genetic disorder. If only one gene is present, an individual is a carrier. What is the probability of two healthy Tay-Sachs carriers having a child that has the disease?
25%
1 in 4.