If k is an integer, which of the following must be an even integer? Select the correct option.
A) k^2-k-1  B) k^2-4k+6  C) k^2-5k+5  D) k^2+3k+8  E) k^2+2k+10
Check the options by plugging in some values ( Preferably smaller integers like 1 and 2 )   A: k^2-k-1 = -1 { If k = 1 }   B: k^2-4k+6 = 3 { If k = 1 }   C: k^2-5k+5 = 1 { If k = 1 }   k^2+3k+8: k^2+3k+8 = 12 { If k = 1 }k^2+3k+8 = 18 { If k = 2 }   E: k^2+2k+10 = 13 { If k = 1 }   Thus the only possible answer is (k^2+3k+8)
<result>D</result>
If k is an integer, which of the following must be an even integer?