Combine like terms: add the coefficients of \(z\). The constant 7 stays as is.<br><br>
&bull; \(2z\) and \(z\) (which is \(1z\)) are like terms.<br>
&bull; \(2 + 1 = 3\), so \(2z + z = 3z\)<br>
&bull; The 7 is a constant and cannot be combined with \(3z\).<br>
&bull; Result: \(3z + 7\)<br><br>
Final Answer: B: \(3z + 7\)