Microservice architecture is an approach where a single application is developed as a suite of small, independent services. Each service runs in its own process and communicates with others, often through HTTP APIs. This decomposition of a large, monolithic application into smaller, manageable pieces is a core principle (C). To fulfill a business requirement, these individual microservices often need to collaborate. This collaboration can be viewed as a "chain" or sequence of calls between services, where one service invokes another to complete a larger workflow (A).

B. Each microservice is designed around a specific business capability; therefore, their functions are distinct and specialized, not the same.

D. There is no prescribed limit to the number of microservices. The quantity is determined by the application's complexity and domain boundaries.

1. Nokia White Paper. (2017). Cloud native: Designing applications for the cloud. Section 2.1, "Microservices," pp. 4-5. This document states, "A monolithic application can be decomposed into a set of microservices... Microservices communicate with each other using APIs." This supports the concepts of decomposition from a monolith (C) and inter-service communication, which forms a chain (A).

2. University of Stuttgart, Institute of Architecture of Application Systems. (2021). Lecture 05: Microservices - Fundamentals, Technologies, and Design. Slides 15-18 ("Decomposition") and 41-44 ("Service Composition"). The courseware explicitly details the pattern of decomposing monolithic applications into microservices (C) and discusses service composition patterns like choreography and orchestration, where services are chained to achieve a goal (A).

3. Pautasso, C. (2017). Microservices in Practice, Part 1: Reality Check and Service Decomposition. IEEE Software, 34(1), 91-98. https://doi.org/10.1109/MS.2017.26. This academic paper discusses the fundamental principle of decomposing systems into microservices (C) and the resulting need for them to interact to deliver end-to-end functionality (A).