Based on a design by Austrian Giovanni Luppis and named for the Englishman who developed it in the 1860s, what is considered the first functional self-propelled torpedo?

Based on a design by Austrian Giovanni Luppis and named for the Englishman who developed it in the 1860s, what is considered the first functional self-propelled torpedo?

Fiske Torpedo
Arkwright torpedo
Davy torpedo
Whitehead torpedo
Stephenson torpedo

The correct answer is Whitehead torpedo