Fill in the blank with a suitable preposition.
She was really scared about the results, so her sister sat _______ her while waiting for the doctor.
The preposition ‘beside’ means to be near or alongside someone/something. In the given context the sister sits near the girl to support or comfort her. Thus option C is correct. On the other hand prepositions ‘to’, ‘below’ and ‘at’ are irrelevant to the context. ‘To’ is used to denote a movement towards a direction/place, ‘below’ is used when something lower than something else, while ‘at’ is used to denote an exact place or spot. One cannot sit ‘to’ her or ‘at’ her since the person is not a place, or sit ‘below’ her since she isn’t an object to sit under. Therefore options A, B and D are incorrect.