Detailed Instructions: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Q: Question: Patients undergoing gastric surgery require vitamin B12 replacement therapy for:
Options: <1> CLH deficiency - which hinders the absorption of nutrients. <2> Excessive loss of this vitamin in the stool. <3> Low intake of food as a result of anorexia. <4> Deficiency in its absorption due to lack of intrinsic factor. <5> Excessive loss of this vitamin in the urine.
A:
4