Final answer:
The question seeking the conditional distribution of allergies among bilingual students cannot be answered without additional data linking language skills and allergy presence. In the absence of specific data, reference to general allergy prevalence figures does not provide a clear answer.
Step-by-step explanation:
The question appears to be asking about the conditional distribution of allergies within a subset of students who speak exactly two languages. However, there is missing contextual data required to determine the correct distribution. Usually, a conditional distribution requires data that correlate to the conditions specified—in this case, information linking language skills to allergy presence. If an empirical study or dataset with the required information was provided, the correct percentages could be calculated or extracted.
In the absence of this specific distribution data, we can refer to the general statistics on allergies mentioned, which suggests a global prevalence of certain allergies like hay fever and contact dermatitis around 20% in developed countries. However, without additional data regarding students who speak two languages, we cannot determine which of the options (1, 2, 3, or 4) is the correct conditional distribution of allergies for these students.