Difference threshold is a minimum alteration in sensory intensity that is noticeable to an observer and can be coded into neural messages. Different threshold is the lowest level of encouragement that is essential to sense that a modification has happened the difference in the intensity between two stimuli that is necessary to yield a just notable difference also known as JND. The just notable difference depends not only on the intensity of the new stimulus but also on the level of stimulation already present which is the more intense the existing stimulus the larger the change must be to be noticeable. 
        
             
        
        
        
CFCs are Chlorofluorocarbon substances used in refrigerants (subtances used to keep other things cold) and in aerosol products. 
they are both relatively nontoxic(nonpoisonous) and nonflammabale - at least as compared to alternatives. 
They are rather volatile - they are not very stable. Therefore it does not make sense to say that they are strong - the correct answer is then strength.
        
             
        
        
        
Answer: Option D. 
Genotype by environment interaction.
Explanation:
Genotype by environment interaction refer to a situation where two different genotypes react differently in an environment. Light skinned humans are at greater risk of skin cancer because they lack melanin which the dark people have and this melanin protect the skin from sun. 
All the choices are correct. Differences in the norm of reaction I.e they react different way. 
Epistasis is when the effect of a gene suppress the other.
Pleiotrophy is when a gene influence another genes phenotipically. These are all genotype enviromr interaction.
 
        
             
        
        
        
Answer:
No negative impact in A and C an would have less mutataion
A is to U C is to G and A-T
Explanation: