Veins .

produce red blood cells
are only found in the heart
usually carry deoxygenated blood
carry blood away from the heart

There is only one answer.

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.

what is shown in the image?

eukaryote

chloroplast

mitochondrion

submitted