Final answer:
During the second trimester, around weeks 16-20, the fetus can be felt moving for the first time.
Step-by-step explanation:
The correct answer is Second trimester. During the second trimester, which occurs during weeks 13 to 28 of pregnancy, the fetus grows and becomes more active. By around week 20, the mother can typically feel the fetus moving for the first time. This is known as quickening.