I have done voluntary work for three years A. I have started to do voluntary work three years ago B. I started to do voluntary work three years ago

B). I started to do voluntary work three years ago.

Explanation:

The second option correctly transforms the given sentence into the past using past indefinite tense. Past indefinite tense is employed to denote the actions that occurred or happened at a particular point of time in the past('started to do voluntary work three years ago'). It is framed using 'subject + V2 + object.' While present perfect tense is employed to denote an action that began in past but still progressed till now. Such actions carry their effects in the present which cannot be possible in the given context as the action took place entirely in the past. Thus, option B is the correct answer.

some attention getter quotes to support your thesis regarding brain work could be the following: :

a. storage capacity of your brain is virtually unlimited.

b. your brain produces sufficient electricity to light-up a small bulb.

c. different brain circuits are involved with reading aloud or silently.

d. your brain by itself does not feel pain.

e. reading allows your brain to download info directly.

f. brains of two musicians performing together can synchronize.