Final answer:
The ASL guest speaker is demonstrating unmarked handshapes, common basic shapes used in many sign languages globally. Option 3 is correct.
Step-by-step explanation:
The concept being demonstrated by the special guest in the ASL class is unmarked handshapes.
These are fundamental handshapes like A, B, and 1 that are common and typically similar across various sign languages worldwide.
Unmarked handshapes are considered the basic or default shapes used in the sign language lexicon, easily produced and recognized, which makes them prevalent in many different sign language systems.
Hence, The ASL guest speaker is showcasing unmarked handshapes, which are commonly used basic shapes in various sign languages around the world. option 3 is correct.