Choose the correct translation.

— Кейт, пойдём с нами в кино!
— Не могу. Я помогаю своей сестре с её проектом о космосе.

• — Kate, let's go to the cinema with us!
  — I can't. I'm helping my sister with her project about space.
• — Kate, let's go to the cinema with us!
  — I can't. I help my sister with her project about space.
• — Kate, let's go to the cinema with us!
  — I can't. I've helped my sister with her project about space.
• — Kate, let's go to the cinema with us!
  — I can't. I've been helped my sister with her project about space.