The first one is commensalism. The second one is mutualism. The last one is parasitism.
        
             
        
        
        
Explanation:
Pancreas functions as both endocrine and exocrine gland. Hence, called as dual function gland or a mixed gland. Exocrine part of pancreas secretes digestive enzymes while, its endocrine part (islets of Langerhans) produce two hormones, i.e. insulin and glucagon.
 
        
             
        
        
        
The answer is A- sperm and egg. gametes are reproductive cells in mammals, so sperm and egg would be the correct.