b><br /> If you remember from the previous chapter, the <code>average()</code>, <code>sum()</code>, <code>max()</code>, and <code>min()</code> methods are implemented as a reduce operation with the <code>collect()</code> method, so the stream can be safely processed in parallel.</p>

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            <p><b>4. The correct answer is D.</b><br /> The call of <code>sequential()</code> turns the whole stream pipeline into a sequential one. In general, we can say that the last call to <code>