A nurse is caring for a client who is in preterm labor and has a new prescription for nifedipine. The client states she is concerned because her father takes nifedipine for his angina pectoris. The nurse should explain to the client that nifedipine works for clients who are pregnant by which of the following mechanisms?It decreases the incidence of bacterial vaginosis, thus preventing uterine contractions.It inhibits uterine contractions by blocking entry of calcium into uterine cells.It decreases the activity within the CNS, which regulates all smooth muscle.It stimulates beta2 receptors in the uterus, which results in decreased frequency of contractions.