Final answer:
The D dimer concentration test is used to diagnose blood clot-related conditions such as pulmonary embolism and deep vein thrombosis but not directly for a dissecting aortic aneurysm.
Step-by-step explanation:
The assessment of D dimer concentration is primarily used to diagnose conditions related to blood clot formation, which includes pulmonary embolism (PE) and deep vein thrombosis (DVT). D dimer is a product that is released when a blood clot gets dissolved in the body, and elevated levels can indicate the presence of an active blood clotting process. Although D dimer can be elevated in a variety of conditions, including inflammation or cancer, it is often used as a part of the diagnostic process to rule out thrombotic conditions such as PE and DVT. However, it might not be as specific for dissecting aortic aneurysm directly, as this condition involves the tearing of the blood vessel wall rather than clot formation. Therefore, the correct answer is B. 2 and 3 only, referring to pulmonary embolism and deep vein thrombosis.