Solution:(c) Students are sending the flyer for the international symposium to institutes all over the country. (Correct)(a) Students are being sent the flyer for the international symposium to institutes all over the country. (Incorrect Tense)
(b) The flyer for the international symposium is sent by students to institutes all over the Country. (Incorrect Sentence Structure)
(d) The flyer is sending the students to institutes all over the country for the international Symposium. (Incorrect Sentence Structure)