A sentence is called a statement if it is either true or false but noth both simultaneously.
Now check options:
A. $\sqrt{3}$ is a prime $\Rightarrow$ False
B. The sun is a star $\Rightarrow$ True
C. 5 is a prime number. $\Rightarrow$ True
D. $\sqrt{2}$ is irrational $\Rightarrow$ True