Which of the Conditions Must Be Satisfied in Order to Justify

Multiple Choice

Which of the conditions must be satisfied in order to justify the inference of a causal relationship between two variables?
i. Concomitant variation
ii. Time order of occurrence of variables
iii. Absence of other possible causal factors
iv. Sterile measurement environment

A) (i)
B) (i) , (iii) and (iv)
C) (ii) and (iii)
D) (i) and (iv)
E) (i) , (ii) and (iii)