What is the scope of the NCh999.Of1999 Chilean Official Standard?

I- The NCh999 standard establishes the general safety specifications for scaffolding.
II- The NCh999 standard replaces the NCh999.EOf78 standard.
III- The NCh999 standard was approved by the National Standardization Institute.
IV- The NCh999 standard was declared an official Chilean standard by the Ministry of Housing and Urbanism.
a) Only I and II are correct.
b) Only II and III are correct.
c) Only III and IV are correct.
d) All statements are correct.