4. (10 points) The teacher asked 5 students: "How many of you reviewed math yesterday?" Zhang: "No one." Li: "One person." Wang: "Two people." Zhao: "Three people." Liu: "Four people." The teacher knew that some of them reviewed yesterday afternoon, and some did not. Those who reviewed told the truth, and those who did not review told lies. So, how many of the 5 people reviewed math yesterday? ( )
A. 3
B. 2
C. 1
D. 0
【Analysis】According to the problem: those who reviewed speak the truth, and those who did not review speak lies. We know that only one of the five people is telling the truth. We can assume that one of the five students is telling the truth and analyze accordingly.

【Solution】Assume Zhang is telling the truth, no one reviewed math, but this contradicts the teacher's knowledge that someone did review yesterday afternoon, so the assumption is incorrect.

Assume Li is telling the truth, only one person reviewed math, which means only he reviewed math, and the other students did not review. The other students are lying, which fits the problem's conditions.

Assume Wang is telling the truth, only two people reviewed math, then among the five students, the other student who reviewed should also say that two people reviewed math, but none of the other students said that two people reviewed math, indicating that Wang is lying.

Similarly, if we assume Zhao or Liu is telling the truth, the other students who reviewed should also match the number of people they mentioned, but they do not, indicating that they are also lying.

Therefore, the answer is: $C$.