Mutation theory was proposed by

The correct option is A Hugo de Vries
Hugo de Vries studied the inheritance of flower colour in Evening Primrose and called the sudden and random appearance of new characters as mutation but the observed mutations were actually chromosomal aberrations. He proposed mutation theory that says that mutations are sudden, random, inheritable and discontinuous variations which serve as raw material for evolution. Mendel conducted hybridization experiments on garden pea plant, Pisum sativum and proposed “Laws of inheritance” on the basis of his results. Lamarck proposed the theory of inheritance of acquired characteristics, using the example of short-necked giraffes evolving into the long-necked giraffes. Kolreuter was first to observe pollination of plants by insects and to study inheritance in plants. The correct answer is A.