Answer with Explanation:
Two genetic concepts were discovered before 1900.
a. preservation of beneficial traits (This was discovered by Charles Darwin in 1859. This theory provided the details about how an organisms survives and adapted to new environment.)
c. calculation of Mendelian inheritance (This was discovered by George Mendel in 1865. This law provided the detail about how genetics is inherited to offspring and what happens when traits move from one generation to other generation.)