Concerning Transport of Genes into Human (Or Animal) Cells, Which

Concerning transport of genes into human (or animal) cells, which, if any, of the following statements is false?
a) Transduction means using viruses to transfer DNA into human (or other animal) cells.
b) Tropism refers to the ability of certain viruses to transduce only certain types of cell, such as hepatocytes, but not neurons.
c) Tropism depends on a virus being able to recognize a specific receptor molecule on the surface of the cell.
d) Transfection means transferring DNA into the cells by any means other than using viruses.