Insulated material can be used for keeping warm, and warm chain is the key to newborn survival. Given these facts, what is the key to newborn survival among the following options:
- deoxyribonucleic acid
 - insulated material
 - empty nest
 - food and shelter
 - cold bed
 - Thyroid-stimulating hormone
 - chemical messengers
 - eating fish


 

  insulated material       