To identify participants for my experimental and control groups, I ask for volunteers to be trained first. Thus, all of the motivated trainees are in my experimental group and the unmotivated employees are in the control group. This is an example of which threat to validity: Question 31 options: Testing History Differential Selection Attrition Question 32 (0.2 points) Listen Given the following lists of instructional objectives and proposed evaluation criteria, determine whether the criteria are: Instructional Objectives Evaluation Criteria Speech Clarity Speech Clarity Active Listening Active Listening Oral Comprehension Oral Comprehension Question 32 options: Contaminated 0% relevant 100% relevant Deficient Question 33 (0.2 points) Listen A manager learns of an employee's poor training performance and then evaluates the employee harshly because of what the manager learned about the training. This is an example of which criterion contamination bias? Question 33 options: Attractiveness bias Opportunity bias Knowledge of training performance Work group characteristics