How to get the bold tag <b> in a string to take effect when displayed on screen?

Question

I have an MVC application wherein I have a string that gets created dynamically from the view model using C# code, there are certain words that need to be marked in bold. For instance, if the string created from C# code is 'This is a test', I wish to display the word 'test' as bold when it is passed from the view model to the cshtml view and is displayed on screen, I tried Regex.replace, which helped me get the text wrapped in bold tags, but after that what I saw on screen was plain text with tags 'This is a < b >test< /b >, while I expected it to be - 'This is a test'. I tried Regex.replace, but that didn't work. Can someone please suggest what should be done in this case ? Below is my code:

content = System.Text.RegularExpressions.Regex.Replace(content, wordToHighlight, "<b>" + wordToHighlight + "</b>", System.Text.RegularExpressions.RegexOptions.IgnoreCase);