Answer: 0 < e < 1.
- A e = 0
- B e = 1
- C 0 < e < 1
- D e > 1
Correct answer: C. 0 < e < 1
Explanation: An ellipse has eccentricity strictly between 0 and 1.
All four conics form a single family distinguished only by eccentricity: a circle is the most "closed" (e=0), an ellipse is an elongated closed curve, a parabola is the borderline open curve (e=1), and a hyperbola has two separate open branches (e>1).
Concept context
Study circles, parabolas, ellipses, and hyperbolas as curves formed by intersecting a plane with a double cone, with their standard equations and key properties.