Alex is conducting a survey for a car company. She decides to start by interviewing some people in her neighborhood. She prepares a questionnaire and emails it to 50 neighbors who own cars. Of those neighbors, 24 respond. Why is this sample likely to be biased?
1. Alex sent a questionnaire by email instead of going door to door.
2. Alex sent the questionnaire only to those who live near her.
3. Not everyone who got the questionnaire responded.
4. Those who got the questionnaire may not have responded on time.