**Answer:** Option **
B **

**Explanation:**

Let the age of the girl is x years.

We know, Average of quantities = |
Sum of all quantities |

No. of quantities |

Three years ago, the average age of a family of 4 members was 14 years.

∴ Sum of ages of all four family members three years ago = 14 × 4 = 56 years

Today, each of the four member age by 3 years.

∴ The total age of the 14 members of the family = 56 + (4 × 3) = 68 years

A girl having been born, the average of the family is the same today i.e. 14 years.

⇒ 68 + x = 70

⇒ x = 70 – 68 = 2

∴ The age of the girl is 2 years.