Given a scientific passage and an answer, generate a question for the given answer.

[Q]: Passage: The Arrhenius definition of acids and bases is somewhat limited. There are some compounds whose properties suggest that they are either acidic or basic, but which do not qualify according to the Arrhenius definition. An example is ammonia (NH 3 ). Its aqueous solution turns litmus blue, it reacts with acids, and displays all the other properties of a base. However, it does not contain the hydroxide ion. In 1923, a broader definition of acids and bases was independently proposed by Danish chemist Johannes Brnsted (1879-1947) and English chemist Thomas Lowry (1874-1936). A Brnsted-Lowry acid is a molecule or ion that donates a hydrogen ion in a reaction. A Brnsted-Lowry base is a molecule or ion that accepts a hydrogen ion in a reaction. A hydrogen ion is commonly referred to as a proton, and so acids and bases are proton donors and proton acceptors respectively according to the Brnsted-Lowry definition. All substances that are categorized as acids and bases under the Arrhenius definition are also defined as such under the Brnsted-Lowry definition. The new definition, however, includes some substances that are left out according to the Arrhenius definition. Answer: acid
[A]: Which type of substance is considered a proton donor in a reaction?

[Q]: Passage: Physics is the study of energy, matter, and their interactions. It is concerned with matter and energy at all levelsfrom the most fundamental particles of matter to the entire universe. Answer: physics
[A]: Which branch of science is the study of energy, matter, and their interactions?

[Q]: Passage: The vagina is a cylinder-shaped organ found inside of the female body. One end of the vagina opens at the outside of the body. The other end joins with the uterus. During sexual intercourse, sperm may be released into the vagina. If this occurs, the sperm will move through the vagina and into the uterus. During birth, a baby passes from the uterus to the vagina to leave the body. Answer: uterus
[A]:
The vagina connects to which internal organ?