Question

is there enough evidence to defend the claim that x-rays caused all the lethal mutations in the offspring of flies exposed to x-rays?
a. yes, because the flies were not exposed to any other source of radiation
b. yes, because the group of flies exposed to x-rays had more lethal mating pairs in their offspring
c. no, because the offspring of flies not exposed to x-rays also had a lethal mating pair
d. no, because the flies exposed to x-rays did not die, meaning they did not have lethal mutations

Explanation:

To claim X - rays caused all lethal mutations, we need to rule out other causes. Option C shows non - exposed flies’ offspring also had a lethal mating pair, meaning mutations can happen without X - rays, so “all” claim is invalid. A is wrong as no other radiation doesn't prove X - rays caused all. B only shows more mutations, not all. D is wrong as flies not dying doesn't mean no mutations in offspring.

Answer:

C. No, because the offspring of flies not exposed to X - rays also had a lethal mating pair