Magento 2 GraphQL add product with additional option to cart

i want to add product to cart with additional option using GraphQL,
i am using below mutation to add product to cart

mutation {
  addSimpleProductsToCart(
    input: {
      cart_id: "{{cart_id}}"
      cart_items: [
        {
          data: {
            quantity: 1
            sku: "tshirt"
          }
          customizable_options:[
          {
            id:1
            value_string:"helsslo"
          }
        ]
        }
      ]
    }
  ) {
    cart {
      items {
        id
        product {
          sku
          stock_status
        }
        quantity
      }
    }
  }
}

this is the responce i get

{
    "data": {
        "addSimpleProductsToCart": {
            "cart": {
                "items": [
                    {
                        "id": "112",
                        "product": {
                            "sku": "Tshirt",
                            "stock_status": "IN_STOCK"
                        },
                        "quantity": 2
                    }
                ]
            }
        }
    }
}