2. Why do the scientists continue to collect data about the ecology of the Hudson River 20 years after the invasion of the zebra mussels?​

This link will hopwfully help, Sorry i have never done this.

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.