Read the following excerpt from the article “Icebergs,” which was posted online by the United States Coast Guard. As you read, consider how some common words used in science texts have multiple meanings. Much has been written about bottle-green icebergs that are sometimes seen in the Antarctic. Several mechanisms have been proposed, but the most likely explanation for the green color is the freezing of organic-rich seawater to the underwater part of the ice shelf from which the iceberg calved. The green ice is exposed after an iceberg breaks free of the shelf and rolls over.

What does the word shelf mean in this excerpt?

Group of answer choices

A)part of glacial ice

B)part of an iceberg

C)a green iceberg

D)part of the ocean

answer; (b); the abolitionist movement;

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.

answer: sure

explanation: i'd love to know everything but that burden is too much to bare.