What is a melanocyte?

Which of the following statements are correct for the tissue shown in the image?
$I$ - Flattened cells with irregular boundaries
$II$ - Secretory cells
$III$ - Single-layered
$IV$ - Found in the walls of blood vessels and air sacs of lungs
$V$ - Functions as a diffusion boundary

The lining of body cavities,ducts,and tubes is made up of $.....$.

Match the terms given in column-$I$ with their feature given in column-$II$ and choose the correct option.

Column-$I$ (Terms)	Column-$II$ (Features)
$A$. Exocrine gland	$I$. They help to stop substances from leaking across a tissue
$B$. Endocrine gland	$II$. Hormones are secreted directly into the fluid bathing the gland
$C$. Tight junctions	$III$. They perform cementing to keep neighbouring cells together
$D$. Adhering junctions	$IV$. Secretes mucus,saliva,earwax,oil,milk,digestive enzymes and other cell products

Read the following statements and answer the question.
$(i)$ It is made of a single thin layer of flattened cells with irregular boundaries.
$(ii)$ They are found in the walls of blood vessels and air sacs of lungs.
$(iii)$ They are involved in functions like forming a diffusion boundary.
Which of the following characteristics of tissue is being described by the above statements?

Desmosomes are a feature of: