In an SAP R/3 system installation, which clients are delivered as standard delivery clients by SAP? Consider the following options: A. Client 000 and client 001 B. Client 001, client 000 and training client 999 C. Client 000, 001 and 002 D. Client 001, 000, 002 and training client 999.

Introduction / Context:
When an SAP R/3 system is installed, certain clients are delivered by SAP as part of the standard installation. Knowing which clients are standard is important for system administrators and consultants, because it influences how they plan customising, training and client copies. This is a common factual question in SAP certification exams and should be memorised.

Given Data / Assumptions:
- The options mention clients 000, 001, 002 and a training client 999.
- Standard delivery clients are created by SAP during installation.
- Other clients can be created later by customers using client copy tools.
- The question focuses on which clients are delivered as standard by SAP, not on best practice use.

Concept / Approach:
In a standard SAP R/3 installation, client 000 is the so called master client that contains standard Customizing, cross client configuration and reference data. Client 001 is a copy of client 000 that can be used as a basis for customer Customizing. These two are delivered by SAP as standard. Other clients such as 002 or 999 may exist in some reference systems or training installations but are not guaranteed in every standard installation. Customers typically create their own project, test and training clients by copying from 000 or 001 according to their needs.

Step-by-Step Solution:
Step 1: Recall from SAP installation documentation that clients 000 and 001 are part of the default system delivery. Step 2: Remember that 000 is the master client and 001 is a standard Customizing client. Step 3: Recognise that client 002 or 999 are not guaranteed in every delivered system and are not always created by SAP. Step 4: Review the answer options and find the one that lists only 000 and 001 as standard delivery clients. Step 5: Select that option as the correct answer.
Verification / Alternative check:
As a verification, think about typical instructions in SAP courses, which often recommend that customers do not change client 000 but perform Customizing in client 001 or a copy of it. They do not usually mention 002 or 999 as standard clients. This practical guidance aligns with the fact that 000 and 001 are the two standard delivery clients and supports the answer.

Why Other Options Are Wrong:
Options that include client 002 or training client 999 treat these as universal standard clients, which they are not. Their existence depends on specific system images or customer installations. The option claiming that only client 000 is delivered ignores the existence of client 001 in a typical SAP R/3 installation. Therefore these options are inconsistent with standard SAP documentation.

Common Pitfalls:
Learners sometimes confuse system images used in training centres, where additional clients may be preconfigured, with the generic standard installation from SAP. Another pitfall is to assume that any client number mentioned in examples must be standard. Remember that only 000 and 001 are reliably delivered in every R/3 system, while others are created or configured by customers or training providers.

Final Answer:
In a standard SAP R/3 installation, only client 000 and client 001 are standard delivery clients shipped by SAP.