Option 2:

Three weeks after traveling to Moscow, Mendeleev's mother died. Mendeleev used this struggle to excel and better focus on his scientific discoveries. Mendeleev's mother said, "Refrain from illusion , and seek divine scientific truth." These were her last words to Mendeleev, he most likely remembered this in times of struggle and used it to help him pushed through. Mendeleev's motivation to continue research may often have been his mother's encouragement while she was alive, letting him know she would have wanted him to continue even still after he was gone.