What explanation best states the importance of ISO certification to businesses?

a$.)$

It is a requirement to make the Global $100$ list.

b$.)$

Forty$-$two percent of businesses state sustainability is part of their business model.

c$.)$

ISO certification is required for businesses to legally operate in most countries.

d$.)$

In some places, only ISO $14000-$certified companies are allowed to bid on government contracts.