If the last three digits of the expression 17²⁵⁶ are a₁a₂a₃ respectively, then the value of the expression is:

a) a₁ +a₂ +a₃
b) a₁ ×a₂ ×a₃
c) a2/1 +a2/2 +a2/3
d) a₁ ⋅a₂ ⋅a₃