There is a picture in which a witch is riding on a broomstick, and in another picture a boy is putting the suitcase in the trunk.
Now the question is...why can't we say that a witch is riding on the broomstick?
And if it should be "A broomstick" then why can't we say "A boy is putting the suitcase in a trunk" of the car? Why "The Trunk is correct"?
Please help me with the article confusion.
1. If the picture being looked at is the only picture, or the first in a series of pictures:
In the first sentence there are three possibilities, depending on how the speaker views the objects in the picture. The first example is probably the most natural, but the other two are possible.
A witch is riding on a broomstick. Both nouns are introduced for the first time.
The witch is riding on a broomstick. = The witch that we see in this picture is riding a broomstick.
The witch is riding on the broomstick. Both nouns are defined as those that we see in the picture.
In the second sentence the most natural sentence is:
A boy is putting a suitcase in the trunk of a car. All the nouns are introduced for the first time, but the car has only one trunk.
Any or all of the indefinite articles can be replaced by a definite article if the speaker considers the noun(s) as being defined by an unspoken idea of "in this picture".
2. If the picture is the second (or following) picture in a series, then "the" will almost certainly be used, because the speaker is now talking about known things