What is the main reason the Do Not Track (DNT) header is not acknowledged by more companies?

What is the main reason the Do Not Track (DNT) header is not acknowledged by more companies?
A . Most web browsers incorporate the DNT feature.
B . The financial penalties for violating DNT guidelines are too high.
C . There is a lack of consensus about what the DNT header should mean.
D . It has been difficult to solve the technological challenges surrounding DN

Answer: C

Explanation:

Reference: https://en.wikipedia.org/wiki/Do_Not_Track