<p>The marketing department is often <strong>conducive</strong> to the sales department due to their necessary collaboration.</p>
<p>The word "conducive" means favorable or helpful in achieving a certain outcome or result. In this context, it means that the marketing department is beneficial or advantageous to the sales department because they need to work together closely.</p>
<p>(A) "hampered" means hindered or impeded, which does not fit the context because it implies a negative effect on the collaboration between the two departments.</p>
<p>(B) "optional" means not required or not necessary. This does not make sense in the context because it contradicts the statement that collaboration between the marketing and sales departments is necessary.</p>
<p>(C) "adjacent" means next to or adjoining. While the marketing and sales departments may be physically located near each other, this word does not accurately convey the idea of collaboration or the relationship between the two departments.</p>