Generally, Wikipedia pages also include references and many of them are legitimate sources of information. In that sense, Wikipedia can be helpful as a starting point for online research more than as an authoritative source of any information. Website 3 -- the National Anti-Vivisection Society: http://navs.org

The National Anti-Vivisection Society appears to be a legitimate organization with many links to established animal welfare organizations such as the Human Society of the United States and ASPCA. On the other hand, it is more of an advocacy site than an information or news site. The main concept of the organization is based on subjective belief and opinions in connection with the relative rights of non-human animals. While that position actually seems appropriate and more justifiable than the opposite position (i.e. insensitivity to the suffering of animals for human benefit), it is not, strictly speaking, based on objective facts. Because the website is so particularly dedicated to its cause, it may not necessarily provide the fullest range of information, even if the information it does present...

Nevertheless, one would expect most of the information provided to be fairly reliable, at least in the sense that it can be checked through links included on the site to government agencies and other objective sources of factual information and some of the conclusions argued by the organization.
Summary

The National Geographic website is likely to be a very reliable source of factual information pertaining to the natural world and issues in the realm of environmental science. The organization has a long and well-known history and its authors are credentialed professionals with advanced degrees and legitimate academic and professional associations. Wikipedia is not a reliable source of factual information simply because its content is not regulated. It may be useful as an informal source of information and as the starting point for formal research. Finally, the National Anti-Vivisection Society appears to be a legitimate organization, but may not necessarily provide a comprehensive analysis of all related issues by virtue of its express mission and values.