Anaphylactic reaction to penicillin is most likely to occur
1. when the drug is administered parentally.
2. within minutes after drug administration.
3. in patients who have already experienced an allergic reaction to the drug.
4. in patients with a negative skin test to penicillin allergy.

(1) (2) (3)

All of the above.

(4) only

(2) and (4)

(1) and (3)