An icon is a symbolic representation of an action to be taken, given in emails or message bars. Icons are metaphorical representations of emotions and feelings which a human is unable to explain in words.
The icon used to represent an attachment is paper clip.
When we click this paper clip icon, it allows us to attach any file including a document or a picture in that particular email. An attachment may also contain a virus, Trojans, worms and other form of malware.
Explanation:
Endogenic forces work towards the middle of the earth...creating pressure causing cracks, pits..
Answer:

✏ Arteries are the vessels that carry blood away from the heart to various organs of the body.Since, the blood emerges from the heart under high pressure, the arteries have thick, elastic walls.
Answer:
Air mass can be described as the volume of air present and the temperature of that mass of air.
Polar air masses are cold. They have less moisture content. The temperature of Maritime Polar air mass ranges from above freezing to below 70 degrees F.
Tropical air masses can be described as air masses that are warm and have a high moisture content. Temperature ranges between 70 degrees F to 90 degrees F.
The grain size is between 1/16 and 2mm