What are the properties that must be satisfied for (X, A, μ) to be a probability space?

• A
  A must be a σ-algebra and μ must be non-negative.
• B
  A must contain all subsets of X and μ must be finite.
• C
  A must not be empty and μ must always equal 0.
• D
  X must be finite and A must be a power set.