Which of the following ideas proposed by Lamarck was later found to be incorrect?

Lamarck thought characteristics, such as a giraffes long neck were caused by them stretching it during their lives and passing that onto their offspring - saying acquired characteristics were passed on through genetics.

What actually happens is natural selection, which means the giraffes born with long necks (by slight mutations or chance) survived better than the ones with shorter necks, as they were able to eat better, so they were able to breed and pass on the genes for long necks where the short necked giraffes died. This theory was thought of by Darwin.