Can we draw the following hypothesis from the context (see options)? 

Context:

How to check engine vacuum hoses<br>Check each hose for bulges and swelling. If a hose feels soft or spongy when you touch it, this can indicate damage caused by your car's oil. [substeps] A swollen hose that is cracked and hard is often caused by heat damage.

Hypothesis: Heat is the primary cause of damaged hoses
Pick from: 1. Yes. 2. It's impossible to say. 3. No.
2.