The teacher advised Ritu to give more attention . . . . . . . . her studies.

The correct answer is: D. in

The preposition “in” is used to indicate a location or position. In this case, the teacher is advising Ritu to focus her attention on her studies. This means that Ritu should pay close attention to her studies and make sure that she understands the material.

The other options are not as appropriate in this context. The preposition “for” is used to indicate a purpose or goal. The preposition “of” is used to indicate possession or ownership. The preposition “at” is used to indicate a location or position.

Here are some examples of how the other prepositions could be used in a sentence:

• The teacher advised Ritu to study for the test.
• The teacher advised Ritu to take care of her studies.
• The teacher advised Ritu to arrive at school on time for her studies.