When you click on the red button to view why the test has failed read the entire failing message, not just the first line. There is info there that tells you what the test was looking for and how to correct it.
In this case the entire failing message says;
The <img> element should responsively resize, relative to the width of its parent element, without exceeding its original size.
Use the “display” style property with a value of “block” for responsive images.: expected ‘inline’ to equal ‘block’
AssertionError: Use the “display” style property with a value of “block” for responsive images.: expected ‘inline’ to equal ‘block’