Is there an error in this code? If so, find the best description of the problem

@font-face {
font-family: ‘Avenir’, sans-serif;
src: url(‘avenir.woff2’) format(‘woff2’), url(‘avenir.woff’) format(‘woff’);
}

• The font file formats are not supported in modern browsers.
• The src attribute requires a comma between the URL and format values.
• There are no errors in the example.
• The sans-serif inclusion is problematic.