1. A pollster wants to gauge national support for a given presidential candidate. Having limited resources, he decides that rather than conducting a survey, he will:

1)Scrape all the comments made during 2015 and 2016 from a user-generated content site like Twitter or Reddit

2)Combine all of the comments from a given user

3)Determine which candidate each user supports from this body of text

What is the name of the problem that he has introduced into this "survey"? 3

(a) Selection bias

(b) Simple random sampling

(c) Randomized response bias (d) Non-response bias