Questions

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.

Donkeys and horses can be breed to make mules and hinnys.

A hinny is a domestic equine hybrid that is the offspring of a male horse, a stallion, and a female donkey, a jenny. It is the reciprocal cross to the more common mule, which is the product of a male donkey, a jack, and a female horse, a mare.

Facilitate means assist someone in their progress or work. Here Help is the only word which is similar in meaning with facilitate. Halt and check are antonyms i.e opposite in meaning of facilitate. 

Hence, facilitate is similar in meaning to help.