image cover in the bootstrap code example

Example 1: image responsive bootstrap 4

<img class="img-fluid" src="" alt=""> //This will make your image responsive

Example 2: How to insert an image in bootstrap 4

<img src="path to image" class="description" alt="Rounded Image">

Example 3: bootstrap image size

.top1 {
    height:390px;
    background-color:#FFFFFF;
    margin-top:10px;
    overflow: hidden;
}

.top1 img {
    height:100%;
}