Based on the Mohs Hardness Scale, the true statement is:
D. You can scratch Apatite with your fingernail.
Here's a brief explanation of each statement:
A. Talc (1) cannot scratch Gypsum (2); it is the softest mineral on the scale.
B. Corundum (9) cannot scratch Diamond (10); diamond is harder than corundum.
C. Topaz (8) can scratch Quartz (7), so this is false; quartz cannot be scratched by topaz, but the statement refers to the reverse.
D. Apatite (5) can indeed be scratched by a fingernail, which is typically rated at around 2.5 to 3 on the Mohs scale, making this statement true.