<p dir="ltr" style="">The sentence structure here is zero conditional. In English, the zero conditional is used for situations that are always true if something happens.<br></p><p dir="ltr" style=""><span><span style="">The form of the zero conditional is: </span></span></p><p dir="ltr" style=""><span><span style="">If/When + [Present Simple], [Present Simple]. </span></span></p><p dir="ltr" style=""><span><span style="">Here are some examples: </span></span></p><p dir="ltr" style=""><span><span style="">If you heat water to 100°C, it boils. </span></span></p><p dir="ltr" style=""><span><span style="">When the sun goes down, it gets dark. </span></span></p><p dir="ltr" style=""><span><span style="">In a zero conditional sentence, the main clause and the adverb clause (“if-clause”) use the simple present tense. Thus, the correct answer is (D) </span><span style="">notice</span><span style="">. </span></span></p>