Answer:
Occurrence. Most auroras occur in a band known as the "auroral zone", which is typically 3° to 6° wide in latitude and between 10° and 20° from the geomagnetic poles at all local times (or longitudes), most clearly seen at night against a dark sky.
Explanation:
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Human chorionic gonadotropin is secreted from the placenta. The correct option is D.
<h3>What is HCG?</h3>
HCG is known as Human Chorionic Gonadotropin.
It is a hormone secreted by the placenta during pregnancy.
The hormone specifically functions to thicken the wall of the uterus in order to be able to support the growing embryo.
It also signals to the body system to halt the process of menstruation.
More on HCG can be found here: brainly.com/question/23308035
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The first link in the food chain
Studying animals in the wild is considered somewhat experimentally out of control because of several reasons.
<u>Explanation:</u>
Study of wild animals can be done using several methods but none will be as effective as studying captivated animals. Using stationary cameras is a method to observe animals in the wild. The stationary nature of the camera makes it necessary for the animals to appear within the field of the camera.
This is difficult in places of low animal density. In addition to that placing camera at a longer distance to watch a larger area decreases the resolution of the images. When it comes to shallow water systems, the field imagery used to track the aquatic species frequently gets affected by issues like sun flicker.
Unmanned aerial vehicles can also be used to track and study animals in the wild. This is good alternative but filming through dense canopies or turbid water is a limitation. Bio loggers can also be used for animal tracking but it is limited by weight since it has to be carried by animals.
