If the major axis of an ellipse is three times the minor axis, then its eccentricity is equal to
Given that the major axis of an ellipse is three times the minor axis.
⇒ a = 3b
We know that eccentricity(e) = 
⇒ 
⇒ 
⇒ 
⇒ 
∴ The correct option is D
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