On the basis of different possible values of α,β and γ and different axial distances or edge lengths a, b and c unit cells are divided into following seven types of three dimensional primitive cells or crystal systems. Which of the following represent triclinic crystal ?
(a) a = b = c, α = β = γ = 90°
(b) a ≠ b = c, α ≠ β = γ = 90°
(c) a ≠ b ≠ c, α ≠ β ≠ γ = 90°
(d) a ≠ b ≠ c, α = β = γ ≠ 90°
