Look at this series: 42, 36, 39, __, 42, 45, 42, 48, ... What number should fill the blank?
Choices:	A) 40	B) 48	C) 46	D) 42	E) 52
42   42   In this series, 3 is added to the previous number; the number 42 is inserted as every third number.
<result>D</result>
Look at this series: 42, 36, 39, __, 42, 45, 42, 48, ... What number should fill the blank?