Which of the following organelles is not considered a component of the endomembrane system?

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

Read the following statements and identify the correct option:
$(A)$ Prokaryotic cells lack a nuclear membrane,chloroplasts,mitochondria,microtubules,and pili.
$(B)$ Eukaryotic cells contain a nuclear membrane,chloroplasts,mitochondria,microtubules,and pili.
$(C)$ Many bacterial cells have small circular $DNA$ outside the genomic $DNA$.

Select the wrong statement from the following.

Which one of the following pairs is correctly matched?

Which dye is used to stain chromosomes?