Designing Quizzes CSS (Cascading Style Sheets)

Question:
Which of the below is the correct way to set a font size?

Option A):
h2 {font-size:200%;} And h2 {font-size:200px;}
Option B):
h2 {font-size:200%;}
Option C):
h2 {font-size:200px;}
Option D):
h2 {font-size:200;}

Correct Answer is Option A):
h2 {font-size:200%;} And h2 {font-size:200px;}