Can any one talk to me im bored

Which of these can an adverbial clause modify?

How can behavioral science be applied in improving public health? a.by tracking a disease to determine its sourceb.by creating promotions that improve health habitscboth by tracking a disease to determine its source and by creating promotions that improve health habitsd.neither by tracking a disease to determine its source or by creating promotions that improve health habits

According to huxley, what is the main reason why people use language inappropriately when discussing war