Appeal is a type of Challenge. Challenge is related to Problem. Problem is related to Difficult. Difficult is related to Very. 
Multiple is related to People. People is related to Protest. Strike is a type of Protest. Disease can Strike. 
Appeal --IsA--> Challenge <--RelatedTo--> Problem <--RelatedTo--> Difficult <--RelatedTo--> Very 
Multiple <--RelatedTo--> People <--RelatedTo--> Protest <--IsA-- Strike <--CapableOf-- Disease 