Context: In ring-porous woods each season's growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before.

Question: What kind of woods always have very clearly marked seasonal growth?
Answer: ring-porous

Question: What size pores form early in ring-porous woods' growing season?
Answer: large

Question: When does the denser tissue the new pores abut come from?
Answer: the year before