In the early 20th century it was known that the cell's nucleus contained two kinds of chemicals. it was discovered that the molecule of inheritance is composed of and not protein as was previously thought.
a. lipids
b. rna
c. dna
d. starch

C. DNA

Explanation:

Prior to the discovery of DNA it was believed that proteins were responsible for carrying the hereditary information of the living organism. However, DNA was discovered in 1869 by German biochemist Johann Friedrich Miescher. His research focused on the white blood cells of pus, as these cells have large nuclei and are easy to isolate from the cytoplasm. The goal was to determine the chemical compounds in the nucleus of cells. The material for his research, pus, was easy to obtain from the bandages used for the wounds.

The biochemist has discovered a material of acidic nature composed of phosphorus and nitrogen. It was a compound, apparently made up of large molecules which it called nuclein.

In 1880 Albrecht Kossel demonstrated that the nuclein contained nitrogenous bases in its structure, hence they were rich in nitrogen as Miescher had shown.

In 1889, Miescher's pupil Richard Altmann proves the acidic nature by obtaining the high-purity nuclein, and called it nucleic acid, DNA.