Which of the following are ways to get a biased sample?

Children who are diagnosed with an autism spectrum disorder can vary in the type and range of symptoms they display, but all children with an autism spectrum disorder have _____.

A. difficulty speaking B. a lack of eye contact C. difficulty understanding others' speech D. difficulty understanding emotions

In sign tracking, an organism approaches a stimulus that signals the presentation of an appetitive event. The approach behavior seems very much like a(n) _____ because it appears to be quite goal directed

A) ?elicited behavior B) ?operant behavior C) ?unconditioned response D) ?neutral response