Step 1: Understanding the Question.
The question asks which hormone is used to stimulate the uterus during pregnancy when normal data compression does not occur.
Step 2: Analyzing the Options.
(A) Progesterone: This hormone helps maintain pregnancy, but it does not induce uterine contractions.
(B) Relaxin: This hormone helps relax the uterus, but it doesn't induce labor.
(C) Oxytocin: Correct — Oxytocin stimulates uterine contractions during labor and is often injected to initiate or stimulate labor.
(D) Vasopressin: This hormone regulates water balance but does not play a direct role in pregnancy stimulation.
Step 3: Conclusion.
The correct answer is (C) Oxytocin, as it stimulates uterine contractions and is used to induce labor.