Should women who are not pregnant and men be concerned about zika infection?

Yes. It is known that Zika can be spread sexually. So, even infected people who do not have symptoms can pass it on to others.

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.

the correct answer is b