To aerate means to mix with:

To aerate means to mix with air. This process is often applied in various contexts, such as gardening, where soil is aerated to allow air to penetrate, promoting the growth of plants by improving oxygen availability to roots. In cooking, aerating can refer to incorporating air into mixtures to create a lighter texture, such as whipping cream or batter.

The other options do not accurately describe the process of aeration. Mixing with water typically pertains to hydration or moisture addition rather than aeration. Mixing with gas could imply a broader range of substances, but air specifically refers to the atmospheric mixture that supports combustion and respiration. Mixing with light doesn’t relate to any common definition of aeration, as it involves energy rather than a physical mixing substance. Thus, the choice of air captures the essence of the term.