In the mid-19th century, symptoms of fatigue, vague aches and pains, low-grade fever, and lack of energy were attributed to a disorder called neurasthenia, which literally translated to

ans.

gregor john mendel is known for study of inheritance in pea plants. he used garden pea plant for his study, having alternative traits for various characters. he performed cross-breeding in pea plants to check how characters are transmitted between parents to offspring, such as cross between pure tall and pure dwarf plant. mendel studied the inheritance patterns in pea plants for various generations.

thus, the correct answer includes options and f).