No Select runtime in Android 4.4.4?

Currently using a Samsung Galaxy Core Prime.

Not the best phone, I know, but it does everything I need it to.

I've read that the ART runtime (when selected) can boost the speed of your phone, so of course I tried it myself.

With developer options already enabled, I see no such option to select runtime.

Instead, I see:
-Take bug report
-Desktop backup password
-Stay awake
-Bluetooth HCI snoop log
-Process stats

And of course, the other options further down that I won't list. "Select runtime" is supposed to be one of the top-listed options, but on my Android 4.4.4, it isn't, so what gives? Is ART the default runtime in 4.4.4 and above?

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