"reduction of stress through relaxation appears to" a. increase arteriosclerosis in those with essential hypertension b. make no difference in the blood pressure of those with essential hypertension c. increase blood pressure in those with essential hypertension d. significantly reduce headaches

d. significantly reduce headaches

Explanation:

Relaxation is a technique that seeks to undo physical, mental and emotional tensions. In the normal state, the human organism remains free of any kind of tension, but through everyday life we acquire tension from various sources. In some cases the tensions originate from thoughts and emotions that are omitted and suppressed in a way that becomes imperceptible, but they influence high levels of stress in the body, which can result in body aches, headaches, among other problems.

Relaxation allows stress levels in the body to be reduced before reaching the point of causing problems to the individual. Because of this, we can say that reducing stress through relaxation allows significant reduction of headaches.

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.