SQL query question

Hi.  I've got a problem that I need to figure out, and I can't seem to do
it with the references I have at hand.

Simplified version of problem:  We have a table.  We'll say it has four
variables, a, b, c, and squelch, all ints.  I want to get all values of
these variables for which:

c is within a certain range of values (call it between 3 and 5).
for any given value of a, c is maximum.
 - and -
for any given value of a for which c is maximal, b is maximum.  That is,
if we have the values of

a b c squelch
1 1 3 5
1 3 3 8
1 1 4 4
1 2 4 6
2 3 5 7

My query should, in this case, get only the last two rows.  (The last one
because there is only one row in which a=2, the next to last because c is
maximal for all values where a=1, and b is maximal for all values where c
= the maximal value for a=1.)

Does this make sense?  The actual question is more complicated than this,
but if I can figure out this, I can get the actual answer.  Please, if you
can, give me an actual sql command that I could use to get the proper
answers from this table.

Thanks a lot for your assistance.

Alloni Kramer