Which sentence must be revised to eliminate the preposition at the end?

If no one answers the door, then please let yourself in.
The top steps are fine, but be careful of the slippery stairs below.
Where are Katelyn and Ella walking to?
Do you know what Naveen was talking about?

answer: e

explanation:

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.

i believe the answer is: b. mr. head had a long, tube-like face with a rounded open jaw and a short depressed nose.

this is because in the un-revised sentence it said that mr. heads face was long and tube-like, and he had a rounded open jaw. this is not a very grammatically correct because of how it seems to drag on with the and, replaced with, with, makes it sound more fluent in the description.

definition was not one of the four methods