The first bird that evolved the ability to fly now had habitats never before available and soon branched out into many different species utilizing different resources, which is an example of

answer; i do believe its (b) 12.5 years of age;

the use of electrical signals that transit messages is know as

even though you have attached neither the chart nor the generalizations, i have located them online. the right answer is d, since they are asking you about a generalization. you can only infer from the chart that between 2008 and 2009 the number of employed workers decreased significantly (from over 115 millions to 107 millions approximately), which signals some type of economic crisis.  

answer; ewing's sarcoma;