A leaf-infecting fungus secretes a chemical that causes the guard cells to remain open thereby enabling the fungus to enter the plant tissue through the stomata. The most likely function of this chemical is

• A

  importing sodium ions into the guard cells.
• B

  exporting potassium ions out of the guard cells.
• C

  exporting water molecules out of the guard cells.
• Correct answer
  D

  importing potassium ions into the guard cells.

Hence, the correct answer is option: 'D'.