Almost half the birds in the yard were brown cardinals and the rest were bright red cardinals, so Jimmy perceived them as two distinct groups of birds. This best illustrates the principle of:.1. Connectedness2. Similarity3. Closure4. Relative clarity

The answer is Similarity

Explanation:

The distinct features of the two groups of birds i.e brown cardinals and bright red cardinals illustrates the principle of similarity. The principle of similarity states that things that share visual features such as shape, size, color, texture, value or orientation will be seen as belonging together or being in a unified group

the answer is:

carbon dioxide