Which of the following solution will have pH value equal to 1.0 ?

Choose the most correct answer: 

ii. Which of the following solution will have pH value equal to 1.0 ?

a. 50 mL of 0.1M HCl + 50mL of 0.1M NaOH

b. 60 mL of 0.1M HCl + 40mL of 0.1M NaOH

c. 20 mL of 0.1M HCl + 80mL of 0.1M NaOH

d. 75 mL of 0.2M HCl + 25mLof 0.2M NaOH