What does it mean when scientists say that living organisms share a universal genetic code?

When scientists say they share a universal genetic code it means that all organisms it can mean either:
 -DNA as the main source of hereditary information in all life forms we know of
 or more likely
 -that all organisms we know of use a three base pair code for the synthesis of proteins, DNA produces mRNA this mRNA is read three base pairs at a time by a ribosome, this is called the genetic code.

Mg is used to measure mass