how to make an 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: bootstrap img src

<img src="..." class="rounded mx-auto d-block" alt="...">

Example 3: How to insert an image in bootstrap 4

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

Example 4: bootstrap image size

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

.top1 img {
    height:100%;
}