The Periodic Law as we know it today owes its development to:

Dmitri Mendeleev

The correct answer is option 4. Dmitri Mendeleev.

The Periodic Law as we know it today owes its development to Dmitri Mendeleev. He is credited with creating the first periodic table of elements in 1869, where he arranged elements based on their atomic masses and observed a periodic pattern in their properties. Mendeleev's work laid the foundation for the modern periodic table, and his insights contributed significantly to the understanding of the relationships among the elements. Therefore, the correct answer is 4. Dmitri Mendeleev