Immediately upon fertilization, a hormone called begins to be released; pregnancy tests measure the level of this hormone in a woman's urine to determine pregnancy

Human chorionic gonadotropin (hCG)

Explanation:

Human chorionic gonadotropin (hCG) is the hormone which can be detected in the blood and urine of a pregnant women. This hormone is made by the placental cells. The blood test or urine test is performed to check the progress of pregnancy that is the development of the fetus. The placenta is the outer membranous layer which covers and protects the developing fetus.

blue

light-years

magnitude

weathering - colorado river carves land in arizona to form the grand canyon. cracks form in a sandstone wall surrounding a house. a marble statue near the science museum is changing color due to rainfall

erosion - after a rainstorm, soil and rock piees litter the roadways. the sand dunes in the sahara desert are changing shape.

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