A farmer sells $1$ litre of milk for Rs$19$. In one month he sells $237$ litres of milk. How much does he earn in a month?

Given:

Quantity of milk sold by a farmer in one month = $237$ litres

S.P. of $1$ litre milk = Rs$19$

To find:

Total earning of the farmer

Calculation:

S.P. of $1$ litre=  Rs$19$

Earning by selling $237$ litre milk =?

By using the cross multiplication method,

Earning by selling 237 litres of milk= Rs$237\times 19$

Solving the multiplication,

$237\times 19=237\times (10+9)$

⟹ $237\times 19=(237\times 10)+(237\times 9)$-----(1)

⟹ $237\times 10=2370$-----(2)

⟹ $237\times 9=2133$-----(3)

Substituting values of (2) & (3) in (1), we get,

$237\times 19=2370+2133$

                 = $4503$

Therefore, the total earnings of the farmer are Rs$4503$.

Hence, the correct option is 'D'.