Which of the Following Statements About Finding a Particular Gene

Which of the following statements about finding a particular gene in a gene library is TRUE?

A) Unless the DNA sequence of the desired gene is known, using an antibody specific for the gene product will not be useful.
B) A DNA probe for the desired gene does not need to be perfectly complementary to the gene of interest so DNA of an homologous gene from another species can sometimes be used as a probe.
C) Generally it is not possible to find a particular gene in a gene library unless it has been expressed; and, therefore, both mRNA and a protein product of the gene must be available to be analyzed.
D) It is almost impossible to find a desired gene in a gene library unless the library was made using a BAC vector.
E) If the gene is not expressed, it will not be possible to find a gene library using a nucleic acid probe.