Questions

Giraffe has the highest blood pressure among animals. 

This is due to the fact that there is a large pressure drop (~100 mmhg) as the blood is transported from the heart, up the neck, to the brain. This is about twice the normal blood pressure of humans (120/80 mmhg).

Fixed expenses are those expenses that do not change when there is a change in production or sales level.

Examples of Fixed Expenses are rent, insurance, payment on loans, salaries, advertising, etc...

When a muscle is contracted and relaxed some amount of heat is released as a by product. 

In the given options, "His stomach rumbled like an approaching train" is an example of Simile.

All the other options are examples of metaphors. 

Simile and Metaphor are both figure of speeches in English which are used for comparing things but the only difference is Simile uses LIKE or AS words in comparing and metaphor directly compares without using any words.