Linnaeus significant development to modern taxonomy is

Carolus Linnaeus is known as "Father of taxonomy" as he made two most important contributions to taxonomy:

1. The system of binomial nomenclature (a 2-part naming method)

2. A hierarchical classification system.

His system of classification consists of a hierarchy of groupings in phylum, class, order, family, genus, and species with the kingdom as the largest and most inclusive group while species as the smallest group.

We still use this system today but we have made some changes like we have added a level in the hierarchy which is domain the broadest level of life and all living things now fit into three domains: Archaea, Bacteria, and Eukarya. Within each domain there are kingdoms.

Thus, his contributions led to the development of modern taxonomy.

option number one would be youre best option

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds