Step 1: Understanding the Question.
The question asks about a substance obtained from marine organisms that is used to treat heart vessel blockages.
Step 2: Analyzing the Options.
(A) Heparin: Correct — Heparin is an anticoagulant used to treat or prevent blood clots, and it is derived from various animal tissues, including marine organisms.
(B) Secera massis: This is not a recognized substance for treating heart vessel blockages.
(C) ARK: This is also not related to the treatment of heart vessel blockages.
(D) None: Incorrect, as heparin is the correct answer.
Step 3: Conclusion.
The correct answer is (A) Heparin, as it is a well-known anticoagulant derived from marine organisms.