Component error

I’m making movement for capsule.

using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    public float speed = 5.0f;
    private Rigidbody rb;

    private void Start()
    {
        rb = GetComponent();
    }

    private void Update()
    {
        float horizontal = Input.GetAxis("Horizontal");
        float vertical = Input.GetAxis("Vertical");

        Vector3 movement = new Vector3(horizontal, 0, vertical) * speed * Time.deltaTime;
        rb.MovePosition(transform.position + movement);
    }
}

but I got this error.

‘Assets\PlayerMovement.cs(8,34): error CS0411: The type arguments for method ‘Component.GetComponent()’ cannot be inferred from the usage. Try specifying the type arguments explicitly.’

I got where was problem: ‘rb = GetComponent();’

how can I solve this component error?

GetComponent() requires you to specify the type of component you’re trying to retrieve!

private void Start()
{
    rb = GetComponent<Rigidbody>();
}