Only 1- the experiment can not show a cause and effect relationship if there are more than one factors contributing to the outcome.
a chemical substance produced and released into the environment by an animal, especially a mammal or an insect, affecting the behavior or physiology of others of its species.
<span>the young of a viviparous animal, especially of a mammal, in the early stages of development within the womb, in humans up to the end of the second month.
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