Question

A scientist notices that a population of birds has decreased dramatically within one year and suspects that a newly introduced snail population may be affecting the bird population. Some individuals within the bird population eat snails, primarily, while other individuals avoid eating snails. Which of the following statements represents a prediction based on a well constructed hypothesis for this observation?
Is snails live in moist habitats then snails will be eaten more frequently by birds
If birds consume snails then they will have higher body mass index than birds that do not eat snails.
If snails that are sick leave their shells so that birds will consume them then snail populations are protected from illnesses
If birds are affected by eating snails then there will be a difference in survival rate of birds that eat snails and those that avoid snails