(2 marks) To ensure a certain level of hygiene in a restaurant, Charlotte consid ered using insecticides to get rid of cockroaches and was trying to model their effect. She observed that i. the more cockroaches there are, the more of them will die due to the insec- ticides; ii. the insecticides are most effective right after they are sprayed, and their efficacy decreases gradually as time passes.Denoting the number of living cockroaches at time it (in units of days) as QUE), d she then modelled the effect of the insecticides by the differential equation 5? 2 _ (t fl)? where t 2 0 refers to the moment when the insecticides were sprayed. Charlotte was aware that this model of hers might generate non-integral number of cockroaches, but she regarded such output as a good approximation for her evaluation of the insecticides. If there were 777 cockroaches when the insecticides were sprayed, how many cockroaches (correct to integers) would there be after 7.5 days? (A) 11 (B) 14 (C) 91 (D) 104 (E) 322 (F) 327 (G) None of the above