"The sun used to smile in my hut". The line is an example of

The line "The sun used to smile in my hut" is an example of personification.
Personification is a figure of speech where human qualities or characteristics are given to non-human objects or ideas. In this line, the sun is being described as smiling, which is a human quality.
The other options - - Apostrophe: Apostrophe is a figure of speech in which someone absent, dead, or non-human is addressed as if they were present and able to reply. This is not the case in the given line, as the sun is not being directly addressed. - Rhetorical Question: A rhetorical question is a question asked for effect or to make a point, rather than to get an answer. The given line is not a question, so it does not fit this category. - Zeugma: Zeugma is a figure of speech in which a word is used in two different ways in the same sentence. The given line does not have such usage.
Therefore, the correct answer is personification.