Theory of saltation was proposed by -

The correct answer is Option (2) → Hugo de Vries

Hugo de Vries believed that evolution takes place by mutation. A mutation is a sudden, large change that can create a new species in a single step. He called this saltation.

(1) Thomas Malthus — Incorrect. He wrote about population growth. His work influenced Darwin.

(2) Hugo deVries — Correct. He proposed that mutation causes speciation in a single step.

(3) Charles Darwin — Incorrect. Darwin proposed natural selection. For him evolution was gradual and worked on small variations.

(4) Lamarck — Incorrect. Lamarck said that organs get stronger with use and weaker with disuse, and that the changes are passed on.

NCERT Extract:
Mechanism of Evolution – “… In the first decade of twentieth century, Hugo deVries based on his work on evening primrose brought forth the idea of mutations – large difference arising suddenly in a population. He believed that it is mutation which causes evolution and not the minor variations (heritable) that Darwin talked about. Mutations are random and directionless while Darwinian variations are small and directional. Evolution for Darwin was gradual while deVries believed mutation caused speciation and hence called it saltation (single step large mutation).”