A

Step 1: Understand the concept of wetting. Wetting occurs when a liquid spreads over a surface, which depends on the balance between cohesive forces (forces between like molecules) and adhesive forces (forces between unlike molecules).
Step 2: In this case, we have water and oil in contact with an oily glass surface. The cohesive forces of oil are stronger than the adhesive forces between oil and glass.
Step 3: This means that the oil molecules are more strongly attracted to each other than to the glass surface, preventing water from spreading on the oil.
Step 4: Therefore, the reason water does not wet the oily glass is because the cohesive force of oil is greater than the adhesive force between oil and glass (Option A is correct).
Thus, the correct answer is A.