I believe the answer to your question is going to be C. 20 
Hope this helps:)
        
             
        
        
        
Answer:
we need PLC(Programmable Logic Units) attached to the sensors  and those sensors will take the signals/values  and transfer them to the cloud .In cloud we store that information and send that information to the web application where user is able to view
Explanation:
it looks like a SCADA system. we can integrate PLC with SCADA
or
for developing PLC we can use c or c++.it contain logic to transfer data to cloud
for cloud storage we can use Microsoft azure which is useful for data storage in sql servers
for web application we can use ASP.Net to interact with cloud and get data from there and display the results to the user on UI
 
        
             
        
        
        
<h2>Many properties can be listed out viz. durability, quality, the sound that it produces also depends on the material that is used, etc.</h2>
Explanation:
1. If you take wood then I would say maple, rosewood, cedar, walnut can be used to make "String instruments". 
Reason: 
The wood that we choose should be perfect and should give long-life to use the instrument.
2. If we consider about strings, then I would suggest that the material that you choose should be "ductile and hard".
Reason:
Thin wires can be drawn. 
3. In case of Brass, it should be "malleable metal", so that the outcome of the instrument will satisfy the need.
 
        
        
        
Answer:
The first check performed by an administrator that it  View the login history.
Explanation:
When user logging into Salesforce it receives an error message into the  screen it view the logging detail which help us take to troubleshoot the problem. The logging history keeps track information like  who is access the system last time ,date etc .login history  also display up to 20,000 records of user logins for the last six months.