Which of the following life processes is important to bring variation in species?

The correct option is Sexual reproduction.

Explanation:

1. Sexual reproduction: This process involves the fusion of male and female gametes from two parents (or within a single organism with two types of gametes). During meiosis, events like crossing over and independent assortment of chromosomes occur. This reshuffling of genetic material produces unique combinations of genes in the offspring, introducing genetic variations within a species.

2. Autotrophic and Heterotrophic nutrition: These are modes of obtaining food and energy. Autotrophic nutrition involves synthesizing organic food from inorganic substances (e.g., photosynthesis in plants), whereas heterotrophic nutrition involves consuming organic compounds prepared by autotrophs. Neither of these processes directly causes genetic variation in species.

3. Transportation: This refers to the movement of water, nutrients, gases, and other substances within an organism's body. It plays a vital role in maintaining life processes but does not affect the genetic sequence or introduce variations.

Therefore, sexual reproduction is the key life process that introduces variation in species, which is essential for evolution and adaptation.