I think lifeguard if you already know how to swim then you don’t have to do any training. And I think being a chef because if you’ve been cooking for like 5 years or something then you don’t need any practice.
<span>Rickets is a:
-bone disease
</span><span><span>Rickets is a skeletal disorder that results from lack of vitamin D, calcium or phosphate</span>
</span>
The answer is a. Because think of the flu for example. The flu vaccine is designed to recognize flu pathogens, then from time time if you have the flu, You body will recognize the pathoges and fight the flu. Some people even become immune to the flu.
