N1 Goi practice question. Synonym of 凌ぐ


Solving some N1-Goi questions I run up to this one.

> 暑さを「 **凌ぐ** 」ために、多くの人が都会を離れて山や海で過ごしている。
>
>   1. つのる
>   2. ふせぐ
>   3. いのる
>   4. ふさぐ
>

I was pretty sure it was the second one 2) ふせぐ" but the solutions provided say
its 1)つのる. I don't get it. xD  
  
Can anyone clarify? Maybe I am missing some detail in the nuance of the
sentence :P

The link can be found here: <https://japanesetest4you.com/japanese-language-
proficiency-test-jlpt-n1-vocabulary-exercise-16/>

