What are two characteristics of a scientific information source that may indicate the information is unreliable?

Scientific information refers to the classification, collection, dissemination, and retrieval of recorded knowledge treated both as a pure and as an applied science. The two features of a scientific information source, which may suggest that the information is not reliable are:  

1. The information is based on data that are not peer-reviewed, that is, the information has not been reviewed by the experts in the field, or is not encouraged by an accord of experts in the field.  

2. The references are not cited, that is, it not clear or not known that from where the information originated.  

the correct answer is:

a population changes in response to a change in the environment.