C. a blog by someone who watched sea turtles hatch
This would not be a good source to use. The blogger may not be considered a reliable source. The blogger may be able to be accurate about what is seen, but may not be in identifying the sea turtles or other information included in the post. Also, watching sea turtles hatch does not give much information about the actual migration patterns. This would only inform Andrew about one location a sea turtle chose to lay her eggs. The other sources are much more reliable and informative because they are produced by experts.