The correct answer is C. Infection
Explanation:
In the excerpt presented, Diego who is the brother of a superhero known as Impervious describes his thoughts as he is informed about his brother's death. One of the main points in this excerpt is who or what killed Impervious or Javier because according to Diego he was an invincible superhero. 
Due to this, the narrator considers possible causes such as an "alien technology" and "damage or infection" but he rules out these options because Aliens were fictional and Javier seemed indestructible not only outside but inside, which proves he was not likely to develop an infection or disease. In this context, one of the weaknesses Diego rules out is an infection.  
 
        
             
        
        
        
Answer:A) a family member with multiple cancers.
Explanation:
A pedigree tree reveals the family history of disease associated with any family member in the past which can be linked to present living members. 
Cancer is a genetic disorder. It is caused by the mutation in one of the functional genes. This leads to abnormal growth of cells in the form of tumor. It is a heritable genetic disorder. The mutation may be pass to the next generation. Thus the appearence of disorder in generations can be traced with pedigree tree. The family member with multiple cancer has acquired cancer from previous generations.