Number of chromosome pairs in humans.

**The reasoning** Humans have **23 pairs** of chromosomes, giving us a total of 46 individual chromosomes. Here's the key principle: **chromosomes exist in pairs** (one from mom, one from dad). Think of it like shoes: if you have 23 pairs of shoes, that's 46 individual shoes total. Similarly: - 23 pairs × 2 = 46 chromosomes - 22 pairs are autosomes (body chromosomes) - 1 pair determines sex (XX for females, XY for males) **Why the wrong options tempt you** **A) 12** — Random guess, no biological basis. **C) 46** — This is the *total number* of chromosomes, not pairs. The question asks for *pairs*, so you need to divide: 46 ÷ 2 = 23. This is the most common trap! **D) 48** — Some apes (like chimpanzees) have 48 chromosomes total (24 pairs). Don't confuse human genetics with our primate relatives. **Quick takeaway** When you see "chromosome pairs," remember: humans have **23 pairs = 46 total**; always check whether the question asks for *pairs* or *total number*.