Correct balanced equation from the following reaction is:
A.$BaC{l_2} + {K_2}S{O_4} \to BaS{O_4} + KCl$
B.$BaCl + {K_2}S{O_4} \to BaS{O_4} + KCl$
C.$BaC{l_2} + KS{O_4} \to BaS{O_4} + 2KCl$
D.\[BaC{l_2} + {K_2}S{O_4} \to BaS{O_4} + 2KCl\]

Hint:As we know that in chemistry, what happens in the chemical reaction is represented by the chemical equation. The amount of reactants reacted and the amount of products obtained are given by the chemical equation. It is important to balance a chemical equation, because the atoms in the equation are just rearranged.

Complete step by step answer:
We have to remember that in the chemical equation, the atoms are neither created nor destroyed. The mass can neither be created and nor destroyed, it is given by the law of conservation of mass. And the chemical equation needs to be balanced by following the law of conservation of mass. In chemical equations, the reaction reactants and the end products are given by the chemical equation in the left side and right side respectively.
If we balance a chemical equation, see the coefficients and change the coefficients, which is numbers given in the in front of atoms in the equation.
$2{H_2} + {O_2} \to 2{H_2}O$
Coefficients
Let us see the options one by one to find the balanced chemical equation. We don’t need to change the coefficients in the given options. We see how many reactants are given and how many products, because the question is asked like that.
Option A. $BaC{l_2} + {K_2}S{O_4} \to BaS{O_4} + KCl$
In the left hand side and the right hand side, $K$ and $Cl$ are not balanced properly. On the left hand side the $Cl$ and $K$ contains subscript $2$.
Option B. $BaCl + {K_2}S{O_4} \to BaS{O_4} + KCl$
If you see the above equation chlorine in the right hand side and left hand side does not balance. And potassium also. So, it is not a balanced equation.
Option C. $BaC{l_2} + KS{O_4} \to BaS{O_4} + 2KCl$
This is also not a balanced chemical equation. $K$ does not balance.
Option D. \[BaC{l_2} + {K_2}S{O_4} \to BaS{O_4} + 2KCl\]
In the above equation, all the coefficients are balanced properly.
The correct Option is D. \[BaC{l_2} + {K_2}S{O_4} \to BaS{O_4} + 2KCl\]

Note:
We need to know that the balanced chemical equation is the fully detailed equation. In balancing the chemical equation, you cannot change subscripts in the chemical equation, if you change the subscripts in the given chemical formula, then the chemical properties and the ratios of the atom changes. Skeletal equation is another type of chemical equation, it needs to be balanced.
e.g., \[Mg + {O_2} \to MgO\]