Which naming convention do you use when create React components?

ComponentA.js

export class ComponentA {
 
  render() {
    return <form onSubmit={this.handleSubmit}>...</form>;
  },
  
  handleSubmit(e) {
    // TODO: handle submit
  }
}

ComponentB.js

export class ComponentA {
 
  render() {
    return <form onSubmit={this._handleSubmit}>...</form>;
  },
  
  _handleSubmit(e) {
    // TODO: handle submit
  }
}

ComponentC.js

export class ComponentC {
 
  render() {
    return <form onSubmit={this._onSubmit}>...</form>;
  },
  
  _onSubmit(e) {
    // TODO: handle submit
  }
}

Personally prefer first one

I used componentC before, but recently changed to ComponentA.