Molluscs, arthropods, and annelids all show which of the following characteristics?

Molluscs, arthropods, and annelids share several important characteristics that highlight their evolutionary relationships and biological similarities. One key characteristic they all possess is a complete digestive system, which allows for specialization of the digestive tract, enabling more efficient processing of food. Additionally, these groups can demonstrate various types of circulatory systems; however, arthropods and most molluscs typically have an open circulatory system, while annelids possess a closed circulatory system, indicating some variability in this trait. Furthermore, during embryonic development, many of these organisms exhibit spiral and determinate cleavage, where the cell divisions are oriented somewhat diagonally and the fate of each cell is determined early in development.

The option indicating all of these characteristics acknowledges the common traits these three groups share, even though they may differ in specific aspects like the type of circulatory system. The inclusion of all three traits ensures a more comprehensive understanding of the similarities among molluscs, arthropods, and annelids. Thus, all these shared characteristics collectively affirm that they are fundamentally linked through their biological processes and evolutionary history.