Which of these statements is written using active voice? donations have been provided to the shelter. the shelter was given donations by them. he often volunteers at the animal shelter. volunteering by him has often been done.

In the active voice, the subject of the sentence is the one doing the action.
Example: George loves Hanna
Here, George is the one doing the action of love

In the passive voice, the subject of the sentence is the one receiving the action.
Example: Hanna is loved by George.
Here, Hanna is the one receiving the action of love from George.

Based on this, let's examine the four choices we have:
1- Donations have been provided to the shelter: the subject is not the one doing the action (providing donations). Therefore, this sentence is in passive voice.

2- The shelter was given donations by them: the subject is not the one providing the action (providing donations). Therefore, this sentence is in passive voice.

3- He often volunteers at the animal shelter: the subject is the doer of the action. Therefore, this sentence is in active voice.

4- Volunteering by him has often been done: The subject of the sentence is not the one doing the action. Therefore, this sentence is in passive voice.

Based on this, the correct choice is "He often volunteers at the animal shelter".