A regular pentagon has a total angle measure of (n-2)180 = (5-2)180 = 540 degrees.
Since each of these angles are the same (that is the meaning of "regular" here), then we know that each of the angles is 540/5 = 108 degrees.
If the two lines from E to B and from D to B are straight lines, then they must trisect (cut into three even pieces) the 108-degree angle at B. That means that the angle in question, angle EBD, must be 108/3
= 36 degrees. Answer B.
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