16. There is a target, with 1 ring, 3 ring, 5 ring, 7 ring, and 9 ring indicating the number of rings hit.

甲 says: “I fired 5 shots, each hit the target, totaling 35 rings.”
乙 says: “I fired 6 shots, each hit the target, totaling 36 rings.”
丙 says: “I fired 3 shots, each hit the target, totaling 24 rings.”
丁 says: “I fired 4 shots, only 1 missed the target, totaling 21 rings.”
It is known that among the four, only one is lying. So, who is lying? $\qquad$ (Fill in 甲, 乙, 丙, 丁)
Answer: C is lying.
Analysis: The property of addition and subtraction of odd and even numbers is that the sum of an odd number of odd numbers is odd, and the sum of an even number of odd numbers is even.
A says: “I fired 5 shots, all hit the target, totaling 35 points.” That is, $9+9+9+1+7=35$. Correct.
B says: “I fired 6 shots, all hit the target, totaling 36 points.” That is, $9+9+9+1+1+7=36$.
Correct.
C says: “I fired 3 shots, all hit the target, totaling 24 points.” The sum of three odd numbers is odd, but the result is 24, which is even.
D says: “I fired 4 shots, only 1 missed the target, totaling 21 points.” That is, $7+7+7+0=21$. Correct.