Consider the expression 7 31 Which statement below is true about the expression A The expression 7 31 is an imaginary number B The expression 7 3i is a complex number where 7 is the real part and 31 is the imaginary part of the expression C The expression 7 31 is a complex number where 3i is the real part and 7 is the imaginary part of the expression D The expression 7 3i is not a number in the set complex numbers