If k is a non-negative integer and 21^k is a divisor of 435,961 then 7^k - k^7 = Choose the correct option.
A) 0	B) 1	C) 42	D) 118	E) 242
4+3+5+9+6+1= 
<gadget id="calculator">4+3+5+9+6+1</gadget>
<output>28</output>
28, so this number is not divisible by 3 and thus not divisible by 21.   Therefore, k=0   7^k - k^7 =1-0= 
<gadget id="calculator">1-0</gadget>
<output>1</output>
1   The answer is 1.
<result>B</result>
If k is a non-negative integer and 21^k is a divisor of 435,961 then 7^k - k^7 =