The correct option is (c) 1
Explanation:

Since, a,b,c are all integers but not all simultaneously equal.
⇒ lf a = b then a ≠ c and, b ≠ c
Because, difference of integers = integer.
⇒ (b - c)2 ≥ 1{as minimum difference of two consecutive integers is (+ 1)} also (c - a)2 ≥ I and we have taken a = b ⇒ (a - b)2 = 0
