16.Researchers at UC Davis finally figured out how the hairy seed pods of the Spanish broom scatter and Sacramento Weed Warriors, like Tess' cousin, conduct removal of the large pesky stands of this scourge of a plant.

Ans: 16.Researchers at UC Davis finally figured out how the hairy seed pods of the Spanish broom scatter and how Sacramento Weed Warriors, like Tess's cousin, conduct removal of the large pesky stands of this scourge of a plant.

1) Researchers have figured out "how . . . and how . . .". Here there is a faulty parallel construction that could be corrected by placing the corresponding "how" in the second noun clause.

2) Tess's should be used. It is the correct form of the possessive according to the Chicago Manual of Style.