Who proposed the law of chemical combination? 

Antoine L. Lavoisier

The correct answer is option 3. Antoine L. Lavoisier.

The law of chemical combination, also known as the law of definite proportions, was proposed by Antoine Lavoisier, a French chemist, in the late 18th century. This law states that in a chemical compound, the elements are always combined in fixed, definite proportions by mass. In other words, regardless of the source or method of preparation, a compound always contains the same elements in the same proportion by mass.

Lavoisier's discovery of this law was a significant advancement in the field of chemistry, as it provided a fundamental understanding of the composition of chemical compounds. It laid the groundwork for the development of modern atomic theory and the concept of chemical stoichiometry.

The law of definite proportions played a crucial role in the transformation of chemistry from a qualitative science to a quantitative science. It provided chemists with a systematic framework for analyzing and understanding chemical reactions and the composition of substances. This law was one of the key principles that led to the formulation of the atomic theory proposed by John Dalton later in the 19th century.