Which option correctly identifies the parts labeled $a$ and $b$ in the given figure?

Which of the following is an incorrect pair?

Match the following columns:

Column-$I$ (Cell)	Column-$II$ (Number of Nuclei)
$P$. Sieve tube element	$I$. Binucleate
$Q$. Paramecium	$II$. Uninucleate
$R$. Typical cell	$III$. Enucleated
$S$. Skeletal muscle cell	$IV$. Multinucleate

Which of the following statements is false?

Given below are two statements:
Statement $I$: Mitochondria and chloroplasts are both double-membrane-bound organelles.
Statement $II$: The inner membrane of mitochondria is relatively more permeable compared to the inner membrane of chloroplasts.
In the light of the above statements,choose the most appropriate answer from the options given below:

In the given figure,what do the parts labeled '$a$' and '$b$' represent respectively?