Which treatment for a heart attack requires threading of a narrow tube or catheter through an artery to the heart? ?

The answer would be: balloon angioplasty

Defibrillation is a treatment for arrhythmia, not for heart attack. Beta-blocker is a drug that can be given by oral or intravenous. Angina pectoris is pain that caused by heart attack. A coronary bypass will need a surgeon to open up the rib cage, catheterization will not enough. 

Nimbostratus is the correct answer.
explanation: nimbostratus clouds are the type of clouds that are mostly likely present on gray, rainy day. these clouds produce continuous rain, snow and there is no thundering or lightening either.