After giving birth to a daughter a year ago, a couple planned to have a second baby - specifically a son. However they have welcomed four more daughters. Zhao Yan, 29, gave birth to the quads in April. The family was happy although they had wanted a son, but the cost of the quartet has given them a headache. "In the first two months, diapers cost more than 1,000 yuan, and now they can finish a can of powdered milk in two days!" said Zhao.

How old is the mother?

A. 28

B. 30

C. 29

（中國日報網英語點津 Helen 編輯）