What is the rest of the question
This might help,the presence of hydrochloric acid creates an acidic environment within the stomach that is needed to convert pepsinogen to pepsin. Mucus that is produced by the epithelial cells of the stomach help protect the lining of the stomach from the corrosive hydrochloric acid and pepsin.
The correct answer is that ferns have two part in their life cycle: Diploid phase and haploid phase
The life cycle of a fern has two parts: sporophyte stage and gametophyte stage. The gametophyte stage of ferns are haploid which releases gametes and the sporophyte stage are diploid that produces spores. This kind of life cycle is known as the "alternation of generation".
If you are talking about frequency in terms of waves, it is in seconds^-1
