The correct answer would be option D.
No, it is not a valid inference because his classmates do not make up a random sample of the students in the school
The population represents all of the students in the school. Apart from his science class there can be students in arts class, music class, literature class and so on. He used convenience sampling by just surveying the students of his science class. The students in science class are those who are interested in science and related topics so these students will be more inclined towards watching a science program. Thus the survey of Johnny does not yield valid result and his inference is not valid.
Thus, option D is the correct answer.
2m = 200cm
4/200
divide both sides by 4:
1/50
Hope this helps ^-^
