The term used to describe the variability among living organisms from different sources, including terrestrial, marine, and other ecosystems, is biological diversity. This includes the diversity within species, as well as the diversity between species and ecosystems.

Geographical diversity (option-1) refers to the variety of physical features and landscapes found in different regions. While this can contribute to the overall biodiversity within an area, it does not specifically address the diversity of living organisms themselves.

Zoological diversity (option-2) focuses specifically on the diversity of animal species. While animals are certainly a key component of biological diversity, this option does not encompass the full range of living organisms, such as plants, fungi, and microorganisms.

Ecological diversity (option-3) refers to the variety of ecosystems present in a given area, including their structure, function, and composition. While it is closely related to biological diversity, it does not specifically address the variability of living organisms themselves.

Therefore, the correct answer is biological diversity (option-4), as it encompasses the variability among all living organisms and their interactions within ecosystems.