How to recover Mac Startup Security Utility? To boot up with external disk, I launched into a startup security utility. 
The standard startup security utility shows the menus like above. 

But my startup security utility only shows the Firmware password protection menu without any options about Secure boot and External Boot. 
How to recover startup security utility? 

OS version: 10.14.5 Mojave
Device version: 2017 MacBook Pro
The way to startup security utility: Press cmd + R on boot
The reason you can't access the Startup Security Utility is because it doesn't exist for your model of MacBook Pro.

More specifically, Startup Security Utility is only available on Mac computers that have the Apple T2 Security Chip. So far the only Macs that have the T2 Security Chip are:


iMac Pro
Mac mini models introduced in 2018
MacBook Air models introduced in 2018
MacBook Pro models introduced in 2018


For more information I refer you to the following Apple pages:


About Startup Security Utility
About the Apple T2 Security Chip