Answer:
1 I think, read the explanation.
Explanation:
Offspring need to carry just one dominant allele from their parents to inherit the polydactyl condition. The probability of the offspring having polydactyly is 50% (2 of the 4) and 50% not having it (normal). This can be expressed as a ratio, 2:2 which can be simplified to 1:1. - found on the internet
 
        
             
        
        
        
Because they want to know the existence of aliens
        
             
        
        
        
Movements of tectonic plates create volcanoes along the plate boundaries, which erupt and form mountains. A volcanic arc system is a series of volcanoes that form near a subduction zone where the crust of a sinking oceanic plate melts.