<p><span style="font-size: 13.008px;">The correct answer is</span><strong> </strong>(C) Because of</p>
<p><span style="font-size: 13.008px;">In this sentence, we need to explain the reason why workers at Marine Public Library have to enter via the south entrance. We can use the phrase "Because of" to indicate the cause or reason for something.</span><br></p>
<p>Option (A) "Now that" is not suitable in this context because it suggests a change in circumstances rather than a cause-and-effect relationship.</p>
<p>Option (B) "Since" can also be used to indicate a cause-and-effect relationship, but it is more commonly used to indicate time or a condition. In this context, "Since" could be interpreted as indicating the time when the maintenance work started, rather than the reason for it.</p>
<p>Option (C) "Because of" is the correct choice because it clearly indicates the reason for the workers having to enter via the south entrance.</p>
<p>Option (D) "Because" is also a possible choice, as it indicates a cause-and-effect relationship. However, "Because of" is more commonly used to introduce the cause or reason in a sentence.</p>
<p>Therefore, the correct answer is (C) "Because of".</p>