Questions

It refers to the possibility for an investor to experience  losses due to  factors that affect the overall performance of the financial markets. Market risk cannot be eliminated through diversification, though it can be hedged against. The sources of market risk include natural disasters, recessions, political turmoil, changes in interest rates and terrorist attacks.

It is a Postbox or a Mailbox which contains thousands of letters or mails or messages.

A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function.

Hence, Cells with similar markers stick together and function as tissues.

The one word substitute for Very pleasing to eat is  Palatable. It means of food or drink that is very tasty, appetizing or pleasant to eat or drink.