Institution: জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় (JKKNIU) Exam: ক ইউনিট || জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় || 2012
Topic: Part of Speech (পদ প্রকরণ), Subject: English Grammar (ইংরেজি গ্রামার)

Best Answer Explained in Below-:

<p data-sourcepos="1:1-1:28" style="margin-right: 0px; margin-left: 0px; white-space-collapse: preserve; word-break: break-word; color: rgb(31, 31, 31); font-family: &quot;Google Sans&quot;, &quot;Helvetica Neue&quot;, sans-serif; font-size: 16px;">The answer is: <span style="font-weight: 700;">adjective</span></p><p data-sourcepos="3:1-3:11" style="margin-top: 1rem; margin-right: 0px; margin-left: 0px; white-space-collapse: preserve; word-break: break-word; color: rgb(31, 31, 31); font-family: &quot;Google Sans&quot;, &quot;Helvetica Neue&quot;, sans-serif; font-size: 16px;">Here's why:</p><ul data-sourcepos="5:1-8:184" style="margin-top: 4px; margin-bottom: 4px; padding-inline-start: 1.125rem; color: rgb(31, 31, 31); font-family: &quot;Google Sans&quot;, &quot;Helvetica Neue&quot;, sans-serif;"><li data-sourcepos="5:1-5:162"><span style="font-weight: 700;">Adverb:</span>&nbsp;An adverb modifies a verb, adjective, or another adverb. In this case, "up" doesn't modify the verb "is late" or any other word in an adverbial way.</li><li data-sourcepos="6:1-6:193"><span style="font-weight: 700;">Adjective:</span>&nbsp;An adjective describes a noun or pronoun. Here, "up" describes the direction (northward in some regions) the train is traveling relative to the speaker, making it an adjective.</li><li data-sourcepos="7:1-7:126"><span style="font-weight: 700;">Noun:</span>&nbsp;A noun is a word that identifies a person, place, thing, or idea. "Up" doesn't function as a noun in this context.</li><li data-sourcepos="8:1-8:184"><span style="font-weight: 700;">Preposition:</span>&nbsp;A preposition shows the relationship between a noun or pronoun and another word in the sentence. "Up" doesn't show a relationship between any nouns or pronouns here.</li></ul>