HTML IMG

Question

How to make a img fit or stretch into a div. Base upon my  css code below, the smaller the height, the image is being cut off

Below is my html code.

<div class="carouselMainStoryContentHeader">

        <a class="carouselMainImage">

                 <img src="images/1.jpg" alt="" />

        </a>

 </div>

CSS code:

.carouselMainImage

{ 

  height: 250px;

}