Fill in the blank with the most appropriate word.
Experiments are often ___________ by scientists.
An action in a sentence can be represented in two ways, namely active and passive voice.
The passive voice always uses the past participle form of the main verb irrespective of any tense. Only the auxiliary verbs depend upon the sentence given in active voice.
The correct answer is B) done as the given sentence indicates the present tense.
Options A, C and D are not correct as the sentence is in the passive voice and present continuous tense , and 'been' cannot be used here respectively,
Experiments are often done by scientists.