title: Question concerning SCJP-6 exam
body: <p>While preparing for the SCJP-6 exam I faced with a difficult issue. I can’t find answer by myself. Please, answer for the question and give short comments:</p>
  
  <pre><code>abstract class A&lt;K extends Number&gt; {
     // insert code here
  }    
  </code></pre>
  
  <ol>
  <li><p><code>public abstract &lt;K&gt; A&lt;? extends Number&gt; useMe(A&lt;? super K&gt; k);</code></p></li>
  <li><p><code>public abstract &lt;K&gt; A&lt;? super Number&gt; useMe(A&lt;? extends K&gt; k);</code></p></li>
  <li><p><code>public abstract &lt;K&gt; A&lt;K&gt; useMe(A&lt;K&gt; k);</code></p></li>
  <li><p><code>public abstract &lt;V extends K&gt; A&lt;V&gt; useMe(A&lt;V&gt; k);</code></p></li>
  <li><p><code>public abstract &lt;V super K&gt; A&lt;V&gt; useMe(A&lt;V&gt; k);</code></p></li>
  <li><p><code>public abstract &lt;V extends Character&gt; A&lt;? super V&gt; useMe(A&lt;K&gt; k);</code></p></li>
  <li><p><code>public abstract &lt;V super Character&gt; A&lt;? super V&gt; useMe(A&lt;K&gt; k);</code></p></li>
  </ol>
  
  <p>Which method can be inserted in the placeholder above?</p>
  
  <p>P.S.
  I tried to look on the specification. Those one was not helpful for me.</p>