Feathers help birds fly and provide insulation, and straight feathers are dominant to curly feathers . Given these facts, a part of birds where what is dominant to curly helps them fly and provides insulation among the following options:
- Animal fur
 - bioaerosols
 - fur and fat
 - Vanes
 - Epidermis
 - sweating
 - staying warm
 - straight


 

        straight 