The correct answer is ruse.
A. thin sheet
B. wafer-like mineral
C. colored glass
The correct answer is (D) A ruse; a scheme or trick to surprise or deceive an adversary; a ploy devised to attain a goal or gain an advantage over another person. Any artifice or trickery to deceive another.
Stratagem comes from French stratagème, Greek stratègèma.
Examples of use:
- Spammers use a variety of stratagems in an effort to infect other computers.
- The use of the Trojan wooden horse was one of history's great stratagems.