Oh gosh. As a violin player I feel so triggered by this question. xD
Let's start by stating what we know the answer cannot be. If it was hit by a mallet like a piano, it's a percussion instrument. Manual just doesn't make sense. A bow is used to pull the string which creates vibration or the sound like a violin. For the most part, violin plucking is done with the fingers. The last option is pick which stringed instruments like guitars can use. The best answer is:
Plucking a stringed instrument may be done with the fingers or a pick.
