Determine if the following statements are true or false, and explain your reasoning for statements you identify as false. 

(a) When comparing means of two samples where n₁ = 20 and n₂ = 40, we can use the normal model for the difference in means since n₂ ≥ 30. 

(b) As the degrees of freedom increases, the t-distribution approaches normality. 

(c) We use a pooled standard error for calculating the standard error of the difference between means when sample sizes of groups are equal to each other.