In my tests, in fact,

/MT and /MD are configuration options for the runtime library settings.

/MD indicates that the runtime library is provided by the operating system as a DLL and is not embedded in the program. As a result, the compiled file is smaller. The library used is MSVCRT.lib. /MT indicates that the runtime library is embedded within the program. This results in a larger compiled file. The library used is LIBCMT.lib.

/LD is used to control the output type as a DLL, and is unrelated to the runtime library.

/MT or /MD can be used together with /LD.

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Since /LD is used to control the output type as a DLL and is unrelated to the runtime library, it is reasonable that this option is not available below.

I believe that the use of /LD should be more implicit, meaning that when you choose to create a DLL project, the compiler should automatically set /LD during compilation.