<p>The correct answer is <strong>(A) learning</strong>.</p>
<p>In this sentence, the verb phrase "looks forward to" is followed by a gerund (a verb form ending in -ing) to indicate the action that Mr. Howe is anticipating. The gerund form "learning" correctly conveys the idea of Mr. Howe's anticipation of gaining knowledge about real estate investment at the seminar.</p>
<p>The other answer choices are not grammatically correct or do not convey the intended meaning:</p>
<p>(B) "learn" is the base form of the verb and does not match the structure of the sentence.</p>
<p>(C) "have learned" is the present perfect tense, which indicates that the action of learning has already been completed. This does not fit the context of Mr. Howe's anticipation of learning at the future seminar.</p>
<p>(D) "having learned" is the present perfect participle, which also indicates a completed action. It does not convey the idea of anticipation or future learning.</p>