Which of the following contains extra-nuclear genetic material?

In the given figure,which components are present in the part labeled $B$?

The plastids which store proteins are

All plastids have essentially the same structure because

Grana present in chloroplast refers to

$S -$ Statement: The flattened sac-like structures arranged like a stack of coins are called grana.
$R -$ Reason: There are $40$ to $60$ grana in a chloroplast.