ldc-crm/database/seeders/SingleOptinSeeder.php

<?php

namespace Database\Seeders;

use App\Models\Answer;
use App\Models\SingleOptin;
use Illuminate\Database\Seeder;

class SingleOptinSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run(): void
    {
        SingleOptin::factory(20)->create()->each(function (SingleOptin $singleOptin) {
            $answerModels = Answer::inRandomOrder()->take(rand(1, 3))->get()->modelKeys();
            $singleOptin->answers()->attach($answerModels);
        });
    }
}