“Chivalry” is what is missing from this riddle; something you can verify just by looking at the old woman and the pregnant woman.
Did you notice in time? How long did it take you?

Advantages Of Riddles: Get A Conclusion
Why are riddles needed in life? A riddle is a problem that checks a person’s knowledge or mental skills. While solving a riddle, the solver has to put the pieces together logically to get the correct or fun answer for a question or riddle. You may question,” What the person gains by doing so?” The answer is very interesting. When he finds the answer, by logically putting the pieces, he will get better solving skills and memory power, which can improve himself. When you solve a riddle, you must notice different pieces and discover their place within the bigger picture. Solving this way might improve your visual-spatial reasoning.