I would say A because it was talking about something in the present but what they were talking about was in past. so I would think A
A list is an R-object that can have a wide range of different items inside of it, including vectors, functions, and even another list.
The head() function lets you display the first observations in a data frame. The method tail() prints the final observations in your data collection in a manner similar to that. Both head() and tail() print a top line called the 'header', which contains the names of the distinct variables in your data collection. The R language's transform() function is used to alter data. The first parameter is transformed into a data frame. A suitable variable name comprises of letters, numbers and the dot or underline characters. The variable name does not begin with a number but rather with a letter or a dot.
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Answer:
The body of water that is most likely to be a marine ecosystem would be an estuary.
Explanation:
An estuary is a widened, often funnel-shaped mouth of a river, where fresh river water and salt sea water are mixed and thus brackish water is created, and where tidal differences can be observed. When a river flows as a system of branches, it is called a delta.
Estuaries often have a great natural value. They typically consist of swallows and salt marshes that are very rich in invertebrates and thus have a great attraction for birds, among other things.
