A company has multiple subscriptions and many resources assigned to each subscription, Administrator wants to know the count of Key Vaults across all the subscriptions, what is the quick way of getting the result?

Answer options:

A.Open Key Vault and Count manually
B.Use Manage view option of Key Vault
C.Use Azure Resource Graph Explorer Query feature
D.Open Key Vault and Apply Filters

Answer: C 
Option A is incorrect because if there are multiple subscriptions, manual counting is not efficient 
Option B is incorrect because even for Manage view, manual counting is required 
Option C is CORRECT because using Azure Resource Graph total count can be retrieved 
Option D is incorrect because Applying Filters would again leads to manual count 
Diagram: 

Reference:

https://portal.azure.com