Answer the questions based on the information given below:
Twenty one participants from four continents (Africa, Americas, Australia, and Europe) attended a United Nations conference. Each participant was an expert in one of four fields, labour, health, population studies, and refugee relocation. The following five facts about the participants are given:
- The number of labour experts in the camp was exactly half the number of experts in each of the other three categories.
- Africa did not send any labour expert. Otherwise, every continent, including Africa, sent at least one expert for each category.
- None of the continents sent more than three experts in any category.
- If there had been one less Australian expert, then the Americas would have had twice as many experts as each of the other continents.
- Mike and Alfanso are leading experts of population studies who attended the conference. They are from Australia.
Which of the following combinations is not possible?
- $2$ experts in population studies from Americas and $2$ experts from Africa attended the conference.
- $2$ experts in population studies from Americas and $1$ expert from Africa attended the conference.
- $2$ experts in refugee relocation from Americas and $1$ expert from Africa attended the conference.
- Africa and Americas each had $1$ expert in population studies attending the conference.