Uche has been in _____ with his pen pal for years.
Answer Details
The correct option is "correspondence". This is because "correspondence" means communication through letters or email and this best fits the context of the sentence. "Exchange" could also work but it has a broader meaning that could imply the exchange of different things such as gifts or ideas. "Favour" and "cord" are not suitable options as they do not fit the context of the sentence.