C.... 376 tbh just took the test and was right
If a person weighs 63.4 KG they will weigh 139.773 but if you estimate it which in most cases you do it would be 139.8 :)
I believe the answer is: Protons and Neutrons
Protons weigh 1 amu while neutrons also weigh 1 amu. I’m not sure if they are talking about how many there is.
