Which of the following axis system is being satisfied by hexagonal crystal system?

• A. a = b ≠ c, α = β = 90o, ϒ = 120o
• B. a ≠ b = c, α = β = ϒ = 90o
• C. a = b ≠ c, α = β = ϒ = 90o
• D. a = b = c, α ≠ β = ϒ = 90o