I believe the activity that will best help prevent the common cold would be D. Covering a sneeze. This will prevent the cold from spreading possibly infecting other people.
The most common effect of long-term use of glucocorticoids is bone loss.
The answer is consumed. Think of a gallon of milk. There will always be an expiration date to let you know that after that date, it becomes too old to drink. This should not be confused with a "sell by" date, which signifies the deadline for each product to be taken off the shelf.