Im having a difficult time ruling out D.
I dont think the stim provides enough evidence for B or D.
B: The fact that babies that cannot hear use their hands to sign, does not mean they cannot make other sounds that develop their vocal tracts. I was thinking, "ok, lets say they are making random sounds, this probably isn't 'speech oriented' because they cannot hear what speech sounds like, but by the same token, how can babies that babble be said to be using 'speech oriented' vocal ability, if this is what is needed to develop language competency?
D: I thought may be correct because the fact that babies that can hear decide to try and speak, rather than sign, shows that the babies are aware of the fact there exists a purpose to speaking.
I went with B anyway, just because the entire stim played up the idea of ability to hear v not hear and their associated actions. This led me to think the answer should incorporate this idea somehow.
Thanks
I am experiencing computer issues, please ignore the post above. I've tried to edit and delet it, but both were unsuccessful.