Question

read the two texts.
text 1
studies have shown that some crows recognize human faces. in one experiment, a group of researchers wore different rubber masks, some of them more dangerous - looking than others. then, the researchers in the more dangerous - looking masks temporarily trapped a group of american crows. after the birds were released, the group of masked researchers returned. the previously trapped crows sounded an immediate alarm and then dive - bombed the researchers—but not all of them. they sought revenge only on those they recognized in the dangerous - looking masks.
text 2
scientists are learning that certain species of crows are highly intelligent. as one of the few non - primates that use tools, crows have been observed using sticks as spears or hooks and even bending wire to make new tools. scientists have also found that crows can form bonds with humans. there are reports of crows bringing \thank you\ gifts to people who have fed them. the odd assortment of gifts might include a button or a screw, or even small bones.
which sentence best combines the main, or central, ideas of both texts?
when crows recognize humans, they often deliver objects as gifts to say thank you for food left out for them.
crows are intelligent creatures that can not only use tools but also form bonds with people and even seek revenge on those who harm them.

Explanation:

Text 1 shows crows recognize faces and seek revenge on those who trapped them (showing intelligence in recognizing and reacting). Text 2 shows crows use tools, form bonds, and give gifts (also signs of intelligence). The second option combines both: tool use (from Text 2), bonding/gifting (Text 2), and revenge - seeking (Text 1) as signs of intelligence. The first option only focuses on gifting from Text 2, missing Text 1's revenge - seeking and Text 2's tool use.

Answer:

Crows are intelligent creatures that can not only use tools but also form bonds with people and even seek revenge on those who harm them.