how make image responsive in bootstrap code example

Example 1: how to make image responsive bootstrap 4

<img src="..." class="img-fluid" alt="Responsive image">

Example 2: image responsive bootstrap 4

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

Example 3: bootstrap image size

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

.top1 img {
    height:100%;
}