Explanation:

option a and b

Colony Collapse Disorder is the phenomenon that occurs when the majority of worker bees in a colony disappear and leave behind a queen, plenty of food and a few nurse bees to care for the remaining immature bees and the queen.

There have been many theories about the cause of CCD, but the researchers who are leading the effort to find out why are now focused on these factors:

• Increased losses due to the invasive varroa mite (a pest of honey bees)
• New or emerging diseases such as Israeli Acute Paralysis virus and the gut parasite Nosema.
• Pesticide poisoning
• Changes to the habitat where bees forage.
• Inadequate forage/poor nutrition.
• Potential immune-suppressing stress on bees caused by one or a combination of factors identified above.