Answers for "bootstrap img fluid"

bootstrap class align center image

class="mx-auto d-block"

responsive image in bootstrap

<img src="..." class="img-responsive">

image responsive bootstrap 4

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

bootstrap img thumbnail

<img src="..." alt="..." class="img-thumbnail">

bootstrap Image thumbnails

In addition to our border-radius utilities, you can use 
.img-thumbnail to give an image a rounded 1px border appearance.

<img src="..." alt="..." class="img-thumbnail">

bootstrap img src

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