To Show order of events and time periods in geological time and Order of events and ages
        
             
        
        
        
Ichthyology is best characterised as Science. None of the other field of studies apply to Ichthyology. 
Pseudoscience are beliefs or theories that have been considered scientific. However, they are disapproved scientifically because lack of facts and evidence. 
Cryptozoology is study of animals that are rumoured to exist. (Bigfoot, Loch Ness Monster, etc) It is connected with pseudoscience.
Mythology can refer to myths or the study of myths. 
As you can see, the study of fish does not apply to any of the area of studies except for Science. Ichthyology applies to Science, because it is a scientific study is different aspects of various species of fish. This includes history, behaviour, and growth.
        
                    
             
        
        
        
Answer:
Explanation:
These proteins, known as growth factors, are signals that stimulate cellular functions such as growth, proliferation, healing and differentiation. In the developing human spinal cord, BMPs are required for the formation of neurons. 
 
        
             
        
        
        
Answer:
D)They both contain carbon, but only nucleic acids contain phosphorous.
 
        
                    
             
        
        
        
The complete question is :
The success of plants extending their range northward following glacial retreat is best determined by _____.
A) whether there is simultaneous migration of herbivores
B) their tolerance to shade
C) their seed dispersal rate
D) their size
Answer: The seed dispersal rate
Explanation: 
The  seed dispersal can be defined as the movement of the seeds away from the parent plant. The ability of the plant to extend is completely dependent on the ability of the plant to disperse its seeds.
Plants have very limited ability, they need vectors to carry its seed from one place to another.
The biotic and abiotic vector both are involved in carrying the seeds which helps in expansion of the trees.
 hence, the correct answer is option C