If a is a positive integer, and if the units digit of a^2 is 4 and the units digit of (a+1)^2 is 9, what is the units digit of (a+2)^2? Choose the most appropriate option:
A) 0	B) 2	C) 4	D) 6	E) 8
If the units digit of a^2 is 4, then the units digit of a is either 2 or 8.   If the units digit of (a+1)^2 is 9, then the units digit of a+1 is either 3 or 7.   To satisfy both conditions, the units digit of a must be 2.   Then a+2 has the units digit of 4, thus the units digit of (a+2)^2 will be 6.   The answer is 6.
<result>D</result>
If a is a positive integer, and if the units digit of a^2 is 4 and the units digit of (a+1)^2 is 9, what is the units digit of (a+2)^2?