Final answer:
Interpersonal attraction in initial relationships is increased by similarity, proximity, and physical attraction, with all of these factors playing critical roles in forming those connections.
Step-by-step explanation:
The factors that increase interpersonal attraction in initial relationships are similarity, proximity, and physical attraction. Each of these elements plays a critical role. Similarity leads to comfortable interactions as people find common ground, making it easier for relationships to flourish. Proximity means that individuals who are physically closer to us and with whom we have more contact are more likely to become friends or romantic partners, simply due to the convenience of frequent interactions. Physical attraction also plays a role, as people tend to be drawn to those they find visually appealing. Thus, the answer to which of the following increase interpersonal attraction in initial relationships is D: All of the above.