How Does the Behavior of the Altered ErbB -Encoded Receptor

How does the behavior of the altered erbB -encoded receptor that is the product of the avian erythroblastosis virus differ from the wild type form of the receptor?

A) The altered receptor behaves in the same way as the wild-type receptor.
B) The altered receptor constitutively stimulates cell growth in the presence and absence of the growth factor.
C) The altered receptor stimulates cell growth in the presence of the growth factor, but not in its absence.
D) The altered receptor constitutively represses growth and cell proliferation in the presence and absence of the growth factor.
E) The altered receptor stimulates cell growth in the absence of the growth factor, but not in its presence.