Your company wants to deploy a set of Azure virtual machines. They want to increase the availability of the underlying machines. You decide to deploy the machines across multiple subscriptions. Would this fulfil the requirement?

Answer options:

A.Yes
B.No

Answer : B 
Subscriptions are used more from a billing aspect for Azure resources. 
For availability you can choose to deploy either across Availability sets or Availability zones 
For more information on Azure availability sets and zones, please visit the below URL 

https://docs.microsoft.com/en-us/azure/availability-zones/az-overview
https://docs.microsoft.com/en-us/azure/virtual-machines/manage-availability