You listen to the heart beating and you hear a "lub-swish- dup".

The swish is caused by:

Select one:

a. A leaky semilunar valve

b. A leaky mitral valve

c. A stenoic mitral valve

d. Closing of the AV valves

B is the answer I did this yesterday

The changes to agriculture in the united states since 1900 is that increased mechanization has increased food production, thereby increasing the need for labor. there has been an increased need for higher speeds of food production due the fact that the population in the united states continues to rise.

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.