Which type of $RNA$ is present in the structure of ribosomes?

The mitochondrial ribosomes in mammals are ........ (in $S$)

Where does protein synthesis occur?

Ribosomes were discovered in animal cells by

All are membrane-bound cell organelles except: $OR$ Which of the following cell organelles lacks a unit membrane?

From the statements given below,choose the correct option:
$A.$ The eukaryotic ribosomes are $80S$ and prokaryotic ribosomes are $70S$.
$B.$ Each ribosome has two sub-units.
$C.$ The two sub-units of $80S$ ribosome are $60S$ and $40S$,while those of $70S$ are $50S$ and $30S$.
$D.$ The two sub-units of $80S$ ribosome are $60S$ and $20S$,and those of $70S$ are $50S$ and $20S$.
$E.$ The two sub-units of $80S$ ribosome are $60S$ and $30S$,and those of $70S$ are $50S$ and $30S$.