Problem: How does the sentence end?

Erin encouraged Kayla to write their essay right away, because 
Answer: Kayla was the less responsible person.

Problem: How does the sentence end?

Playing in the snow was fun for Betty but not Elena because 
Answer: Elena grew up in the west coast.

Problem: How does the sentence end?

The doctor was able to diagnose the disease but not the tumor since the 
Answer: tumor was hidden.

Problem: How does the sentence end?

People voted whether Robert's fancy red costume or Aaron's simple blue costume was the best superhero outfit, after the fancy red one won 
Answer:
Robert was happy.