What is the value of the given expression (a + b + c)² - a²-b²-c²?

Correct option is B

Given:
(a + b + c)² - a²-b²-c²
Formula Used:
(a + b + c)²= a² + b² + c² + 2(ab + bc + ca)
Solution:
(a + b + c)² - a² - b² - c²
=a² + b² + c² + 2(ab + bc + ca) - a² - b² - c²
=2(ab + bc + ca)
Alternate Method:
Concept: Value putting method
Let a=2 , b=1, c=1
(a + b + c)² - a²-b²-c²=(2+1+1)²-2²-1²-1² =16-6=10
Now by checking option (b)
2(ab + bc + ca) = 2 (2×1+1×1+2×1) = 2 (2+1+2) = 2×5 = 10
L.H.S = R.H.S