Final answer:
D. doubled. In the last thirty years, the number of human resource managers in Canada has doubled.
Step-by-step explanation:
In the last thirty years, the number of human resource managers in Canada has doubled.
This means that the number of human resource managers in Canada has increased by a factor of 2. For example, if there were 100 human resource managers thirty years ago, now there would be 200.
This trend suggests a growth in the importance of human resource management in organizations, as more professionals are needed to handle the increasing complexity of managing human resources.