Fact 1: Shivering occurs when many muscles contract a little bit all at once. Fact 2: Involuntary contractions, shivering, cause the production of heat. Given the two facts above, what occurs when many muscles contract a little bit all at once?

Select from:
(i) the production of cells;
(ii) preventing heat transfer;
(iii) To keep their body heat.;
(iv) the production of heat;
(v) Generating heat;
(vi) recovery time from fatigue;
(vii) the production of cold;
(viii) the production of skin;
The answer is:
(iv)