Based on the newspaper reports, (1)/ we can conclude that (2)/ many accidents caused by reckless driving. (3)/ No error. (4)

Answer

3

Explanation

are will be used after accidents because - The sentence is in Passive Voice. The basic structure of a Passive clause is as follows:

It is also a general statement, hence, the Aux. Verb will be used in Simple Present Tense.
Hence, many accidents are caused by reckless driving is the right usage