Which of the following is not a valid statement?

$9.$

a$.$ Database design refers to the activities that focus on the design of the database structure that will be used to store and manage end$-$user data.

$10.$

b$.$ A database is a shared, integrated computer structure that stores a collection of user data and metadata.

c$.$ Data redundancy exists when the same data is stored unnecessarily at different places.

d$.$ Raw data is the collection of processed knowledge.