A. 0
B. 1
C. 3
D. 4
E. 6

Answer: D

Explanation:
Unit place of 3972^8- 1832^3
The cycle of 7 is 7,9,3,1 so 7^{28} will give unit digit 1 as 28 is divisible by 4.
The cycle of 3 is 3,9,7,1 so 3^{23} will give unit digit 7 as 3 is the remainder when we divide 23 by 4.
So, 1-7 gives us 4.

Hence, the answer is D.

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