Structural damage from seismic vibrations would be worse where buildings were built to code on solid rock where older buildings were built on a thick layer of sediment where the focus is about 800 kilometers below the surface where buildings are made mostly of wood

The answer to this question is the second item in the choices which is "where older buildings were built on a thick layer of sediment". We know that seismic vibration is the sound or movement generated from the ground. This happening is unwanted and cannot be controlled. Once this occurs in higher magnitude it would cause great damage to our structure were buildings made of rock collapse. 

May consider a group  g=({0,1},+)g=({0,1},+)where  ++  will work as the xor operator like we work in boolean algebra. note here, that ‘00’ and ‘11’ are not the usual 0 and 1 that we work with everyday. the elements are  called  ‘00’ and ‘11’ and  may not mean  zero (nothing) and one (single). ‘00’ is the identity for the given binary operator +, meaning that any element operated with ‘00’ gets us that element itself.  for a set  ss  in  g′g′  having more elements than just  {0,1}{0,1}  the values for  a+b∈sa+b∈s, such that  a∈s,b∈sa∈s,b∈s, have to be first defined, only then can you determine the value of  1+11+1. the answer could possibly have been  22  if oanswer is25,000