Here's how to determine the complementary DNA strand for "TCG AAG":

* Base Pairing Rules: DNA bases pair up in a specific way:

* Adenine (A) pairs with Thymine (T)

* Guanine (G) pairs with Cytosine (C)

* Complementary Strand: To find the complementary strand, we simply replace each base with its partner:

* TCG AAG becomes AGC TTC

Therefore, the complementary DNA strand of TCG AAG is AGC TTC.