The human body is organized in a hierarchical arrangement, as shown below.

what structure is represented by the fourth image int he above series?

1.organism

2.organ system

3.cell

4.tissue

The appropriate answer is 2. an organ system. the first image shows a cell. Cells are the smallest subdivision of an organism considered to be alive or living. The second image represents tissue. Tissue is a collection of specialized cells that have a specific function. Connective and muscular are examples of tissues. The third image shows an organ and this is an anatomical structure that has specialized tissue and a recognizable structural boundary. The fourth image shows an organ system which is a group of organs working together to carry out a specific function such as digestion. The last image represents the organism.

Explanation: An air mass can be define as the body of air whose properties such as humidity, temperature and other features are homogeneous. The air mass can vary according to the location. The warm front is formed the warm air mas replaces the cold air mass.The cold front is formed when a cold air mass replaces a warm air mass. The stationary front can be define as a weather condition in which the cold and hot air masses lie in opposite directions and neither of them are capable of displacing each other. As, a result of this a static weather condition develops. In stationary front the weather remains mild. In occluded front is formed when a cold air mass overtakes a warm air mass and goes underneath it.  

On the basis of the above description, the following are the matches:

A.) warm  2.) A warm air mass advances on a cold air mass, causing rain.

B.) stationary  3.) Air masses that are close in temperature collide, typically leading to mild weather.

C.) cold 1.) A cold air mass advances on a warm air mass, causing rain.

D.) occluded  4.) Three air masses meet, usually leading to strong winds and heavy rain.