That was correct. it was letter choice b
        
             
        
        
        
Answer:
The correct answer is - Polymer (macromolecules), monomer (building blocks
Explanation:
Polymers are comparable to the train as polymers are made up of several monomers linked together to carry more but can be removed from the polymer if required similarly the train cars that are comparable to the monomers or building block are joined together but can be taken off.
Macromolecules are polymers that are made up of joining monomers together and makes large molecules. Macromolecules like carbohydrates are made up of monosaccharides as monomers, proteins are made up of amino acids as monomer or building block, lipids are made up of fatty acids and nucleic acid are made up of nucleotides.
 
        
             
        
        
        
A. for cooking food and transmitters
        
             
        
        
        
Answer:
Transitional fossils show how a particular taxa accumulated adaptations to fit particular environments and/or ecological niches
Explanation:
Transitional fossils are fossilized remains of taxonomic groups/species that illustrate an evolutionary transition between a known version of a taxa/species and the current taxa/species. Transitional fossils are fundamental because they can be clearly differentiated from the ancestral group as well as of its derived descendant group. For example, there exist transitional fossils known as "mammal-like reptiles"(i.e., therapsids that gave rise to the true mammals), which are clearly different from current mammals.
 
        
             
        
        
        
<span>The tracheae possibly have evolved directly from the book lungs</span>