You can obtain the answer . . . . . . . . adding the date of birth to this figure. A. to B. by C. on D. in

The correct answer is: B. by

The word “by” is used to indicate a means or method. In this case, the date of birth is the means by which you can obtain the answer.

The other options are incorrect because they do not make sense in the context of the sentence.

• The word “to” is used to indicate a destination or goal. In this case, the date of birth is not a destination or goal.
• The word “on” is used to indicate a specific time or date. In this case, the date of birth is not a specific time or date.
• The word “in” is used to indicate a location or position. In this case, the date of birth is not a location or position.