Answer:
Observability
Step-by-step explanation:
In this question, the factor affecting the velocity of diffusion is observability.
This mathematical concept concerns the knowledge of an internal state of a system by the knowledge of its external outputs. (such as the white phone that determined the use of the ipad even when it could not be observed)
The dissemination occurred through the innovation of the brand and creation with consumers about the relative advantages of the brand and the diffusion of a symbolism that induces the use of a product by fad and added value.