The earliest record of point mutation is

The correct option is B Short legged sheep by Seth Wright

Seth Wright, 1791, observed an unusual short-legged sheep in the flock which was beneficial as it could not cross the fences and damage the crop. Thus a line of short-legged sheep was developed, the Ancon breed. Morgan, 1910, observed white eyed male Drosophila in otherwise red-eyed wild type generation. A cross between white eyed male and red eyed female produced both red-eyed and white eyed male and female progeny. George Beadle and Edward Tatum, 1941, exposed spores of the fungus Neurospora crassa to X-rays and other agents, which damage DNA and cause alterations in DNA sequence (mutations), to produce nutritional mutants. Esther and Joshua Lederberg, 1952, showed that many mutations are random, not directed. They worked on antibiotic resistant mutants in E. coli. The correct answer is option A.