Three different proteins ( $\mathbf{X}, \mathbf{Y}$ and $\mathbf{Z}$ ) that are known to be transported from the cytoplasm into different organelles were studied. Protein $\mathbf{X}$ was found to be localized in the matrix of mitochondria, protein $\mathbf{Y}$ inside the lumen of endoplasmic reticulum and protein $\mathbf{Z}$ in the nucleoplasm. Based on this information, the correct option is

• Correct answer
  A

  While $\mathbf{X}$ and $\mathbf{Z}$ have to cross two bilayers, $\mathbf{Y}$ has to cross one bilayer.
• B

  While $\mathbf{X}$ and $\mathbf{Y}$ have to cross two bilayers, $\mathbf{Z}$ has to cross one bilayer.
• C

  All the three proteins $\mathbf{X}, \mathbf{Y}$ and $\mathbf{Z}$ have to cross two bilayers.
• D

  While $\mathbf{Y}$ and $\mathbf{Z}$ have to cross two bilayers, $\mathbf{X}$ has to cross one bilayer.

Hence, the correct answer is option: 'A'.