Q:

Washing your hands at regular intervals could be the most effective method to staying healthy and protecting yourself from various ailments.

(I) is the most effective way of staying
(II) can be the most effective way to stay
(III) has the effective effect to stay

• 1
  Only (I) is correct
• 2
  Only (II) is correct
• 3
  Both (I) and (III) are correct
• 4
  All are correct
• 5
  No correction required