Explanation:

In Azure App Service, a Web App must be hosted in an App Service Plan (ASP) that meets three key compatibility conditions:
The App Service Plan and the Web App must be in the same region.
The operating system (Windows or Linux) of the App Service Plan must match the Web App type.
The runtime stack of the Web App must be supported on the App Service Plan's OS.
Let's apply these rules to the scenario:
# App Service Plans:
Name
Operating System
Location
ASP1
Windows
West US
ASP2
Windows
Central US
ASP3
Linux
West US
# Web Apps:
Name
Runtime Stack
Location
WebApp1
NET Core 3.0
West US
WebApp2
ASP.NET 4.7
West US
1## WebApp1 (.NET Core 3.0, West US)
Region requirement: Must use an App Service Plan in West US # # ASP1 and ASP3 qualify.
Runtime requirement: .NET Core 3.0 supports both Windows and Linux App Service Plans.
(Microsoft Learn: ".NET Core apps can run on both Windows and Linux App Service plans.")
# Therefore, WebApp1 can use ASP1 (Windows, West US) or ASP3 (Linux, West US).
# Answer: ASP1 and ASP3 only
2## WebApp2 (ASP.NET 4.7, West US)
Region requirement: Must be in West US # # ASP1 and ASP3 qualify.
Runtime requirement: ASP.NET 4.7 is a Windows-only framework; it cannot run on Linux App Service Plans.
(Microsoft Learn: "ASP.NET (non-Core) apps require a Windows-based App Service Plan.")
# Therefore, only ASP1 (Windows, West US) is compatible.
# Answer: ASP1 only
# Final Verified Answers:
Web App
Compatible App Service Plans
WebApp1
ASP1 and ASP3 only
WebApp2
ASP1 only
Microsoft Documentation Extract (Azure App Service):
"App Service plans must be in the same region as the web app."
"Windows App Service plans host ASP.NET, .NET Core, and Node.js apps."
"Linux App Service plans host .NET Core, Node.js, Python, PHP, Java, and custom containers."
".NET Framework (ASP.NET 4.x) applications can only run on Windows-based App Service plans." Hence, the verified and Microsoft-official answer is:
# WebApp1 # ASP1 and ASP3 only
# WebApp2 # ASP1 only