Why does the smoothness of operation of an engine increase with a greater number of cylinders?

Consider the binary relation on the set A={0,1,2,3,4} defined as follows. D={(x,y) in AxA:x>y+3}. Then the cardinality of D is?

Let > be the strict order in the Real numbers. Then I> is?

Let X={x,y,z} and B the subset of XxX shown in the graph.  Then, B is

Spongy bone is found in:

  In the diagram, where is the reticular region of the dermis?

  In the photo, which layer is the stratum spinosum?

Which of the following in NOT considered a function of the skeletal system?

   What overall conclusion did the researchers make?  

   Why could multiple subgroup analyses be a concern?