Final answer:
The signs for 'mother' and 'grandmother' in sign language use different handshapes but have similar motions.
Step-by-step explanation:
The signs for 'mother' and 'grandmother' in sign language are similar but not identical. The correct answer is c) They use different handshapes but similar motions. In sign language, the sign for 'mother' typically involves placing the open hand near the chin and moving it forward slightly, while the sign for 'grandmother' includes the same motion but with an additional movement of the hand away from the body. Although the handshapes may be different, the gestures and motions used are similar.