<p>I swear this sentence seems correct to me but there is an error :/ And I cannot understand why it is wrong. I write the correct answer at the bottom.</p>
<p>He was <somewhat> (A) uncertain about <how to="" use=""> (B) the new machine and <asked for=""> (C) <more specific=""> (D) instructions be sent. <no error=""> (E)</no></more></asked></how></somewhat></p>
<p>(C)</p>