Which two sentences about inferences based on numeric variables are true? A strong positive or negative correlation can be used to prove a causal relationship, while the absence of correlation can be used to rule out a causal relationship. The absence of correlation can be used to rule out a causal relationship, but the presence of a strong positive or negative correlation does not prove a causal relationship. Strong correlations between two variables are sometimes explained by the influence of a third lurking variable that has a causal relationship with both variables. If a variable is known to be affected by multiple causes, its strong positive or negative correlations with other variables are likely to be spurious.