Change inactive class active class and apply for selected element only
<p>in given example I used class .inactive for not selected link element, I want to convert .inactive to .active and apply to active link element, means there will be only one .active in list.</p>

<p>HTML :</p>

<pre><code>&lt;div class="tab-header clearfix"&gt;
  &lt;ul id="tabs"&gt;
    &lt;li&gt;&lt;a id="tab1"&gt;About the App&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a id="tab2"&gt;PLO&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a id="tab3"&gt;Prerequisites&lt;/a&gt;&lt;/li&gt;
  &lt;/ul&gt;
&lt;/div&gt;

&lt;div class="tab-container" id="tab1C"&gt;
  tab-container 1
&lt;/div&gt;

&lt;div class="tab-container" id="tab2C"&gt;
  tab-container 2
&lt;/div&gt;

&lt;div class="tab-container" id="tab3C"&gt;
  tab-container 3
&lt;/div&gt;
</code></pre>

<p>CSS :</p>

<pre><code>.tab-header {
  background: white;
  border-bottom: 1px solid #ededed;
}
.tab-header #tabs {
  width: 100%;
  height: 30px;
}
.tab-header #tabs li {
  float: left;
  list-style: none;
  width: 30%;
  box-sizing: border-box;
}
.tab-header #tabs li a {
  color: #ffffff;
  padding: 0 5px;
  display: block;
  text-decoration: none;
  outline: none;
  text-align: center;
  line-height: 30px;
  font-size: 13px;
  cursor: pointer;
  background: blue;
}
.tab-header #tabs li a.inactive {
  color: blue;
  background: white;
}
.tab-header .tab-container {
  clear: both;
  width: 100%;
  padding-top: 20px;
}
</code></pre>

<p>jQuery :</p>

<pre><code>$('#tabs li a:not(:first)').addClass('inactive');
                $('.tab-container').hide();
                $('.tab-container:first').show();

                $('#tabs li a').click(function(){
                    var t = $(this).attr('id');
                    if($(this).hasClass('inactive')){ //this is the start of our condition 
                    $('#tabs li a').addClass('inactive');           
                    $(this).removeClass('inactive');

                    $('.tab-container').hide();
                    $('#'+ t + 'C').fadeIn('slow');
                 }
                });
</code></pre>

<p><strong><a href="https://jsfiddle.net/alpeshlahad/dtfbfqbd/3/" rel="nofollow">JSFiddle Here</a></strong></p>