Which stage of the human sexual response cycle includes changes in the pelvic region, general physical arousal, and increases in heart rate, muscle tension, blood pressure and rate of breathing?

The answer to this question would be: excitement phase

In excitement or arousal phase, the body will increase heart rate, muscle tension, blood pressure and rate of breathing. In this phase, the human body is changed to accommodate the sexual intercourse. The higher blood pressure and heart rate is an important factor to make the penis erect. Muscle in the vagina would be tightened and vasocongestion will increase the cl*itoris size.