Question

The boys were very happy with _______ performance last night.
their
there
they're

Answer 1

\(\color{#0cbb34}{\text{Originally Posted by}}\) @cpl106
thier?
\(\color{#0cbb34}{\text{End of Quote}}\)
The word "Their" is used for one person not two so that would be incorrect

Answer 2

Politely disagree with the previous response. the subject is "boys" (which is plural) so their is appropriate.

"they're" doesn't work (they're = they are. "they are performance" doesn't make sense)

"there" also doesn't work, because there is used to show location. the sentence is assigning ownership of the performance to the boys, so the possessive "their" is the only logical choice.