If a·b·c·d=450, where a, b, c and d are positive integers, and a<b<c<d, which of the following could be the value of d−a?  Select
A) 9  B) 10  C) 11  D) 13  E) 15
prime factorize : 450 = 2*3*5*15   Hence a = 2 and d = 15 .   Hence answer is  15 - 2= 
<gadget id="calculator"> 15 - 2</gadget>
<output>13</output>
13   Answer 13
<result>D</result>
If a·b·c·d=450, where a, b, c and d are positive integers, and a<b<c<d, which of the following could be the value of d−a?