Final answer:
The dense granules of platelets contain adenosine diphosphate (ADP) and calcium ions (Ca₂⁺), essential for blood clotting and platelet plug formation.
Step-by-step explanation:
The dense granules of platelets contain a variety of substances that are crucial for the blood clotting process. Among these substances are adenosine diphosphate (ADP), which is important for the accumulation and adhesion of platelets at the site of an injury, potentially expanding the platelet plug. Another notable substance is calcium ions (Ca₂⁺), which play various roles, including binding to clotting factors and aiding in the coagulation cascade. Therefore, the correct answer to the question is 1) ADP and Ca₂⁺.