VCs fund typically have 15 or so investments per fund. Why that number? Why not just 1 or 2 big ones? Or say 50 small ones?

VC funds typically specialize in an industry sector, such as, tech, or health, or education, or manufacturing, or finance. Why the industry specialization. Why not diversify?

VCs prefer a regional approach as well. Why? Why not invest across the continent or even the world for that matter?

VCs prefer to focus on a certain stages or rounds of a company's fundraising, why?