You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.

Example input: Optical mice use an LED and a camera to rapidly
capture images of the surface beneath the mouse.
The infomation from the camera is analyzed by a
DSP (Digital Signal Processor) and used to detect
imperfections in the underlying surface and
determine motion. Some materials, such as glass,
mirrors or other very shiny, uniform surfaces
interfere with the ability of the DSP to
accurately analyze the surface beneath the mouse.

Since glass is transparent and very uniform, the
mouse is unable to pick up enough imperfections in
the underlying surface to determine motion.
Mirrored surfaces are also a problem, since they
constantly reflect back the same image, causing
the DSP not to recognize motion properly. When the
system is unable to see surface changes associated
with movement, the mouse will not work properly.
Example output: why doesn't an optical mouse work on a glass
table?
Example explanation: The passage talks about the glass and mirror surfaces beneath the optical mice and how the mouse is unable to pick up enough imperfections in the underlying surface to determine motion. The last line of the passage explains why the mouse will not work properly on these surfaces. Thus it is a positive example.
Q: The New England Journal of Medicine recently published a study suggesting that parents should wait 18 to 23 months after a full-term birth before conceiving again. Interestingly enough, the average age gap between siblings in America is about two and a half years -- which means we must be following this advice! I personally have two sisters, one 6 years older and the other 11 years older, and we get along famously. You have to worry about competition between siblings when the age gap is too small; but with families with wide gaps in age between the siblings, you have to worry that they'll be raised almost like one "only child" after another. Best,
'k.
A:
What's the best age gap between siblings?