If a sphere with radius \(r\) is inscribed in a cube with edges of length \(e,\) which of the following expresses the relationship between \(r\) and \(e?\)
A. \(r=\dfrac12 e\)
B. \(r = e\)
C. \(r = 2e\)
D. \(r=\sqrt{e}\)
E. \(r=\dfrac14 e^2\)
Answer: A
Source: Official Guide