Task: Question Answering
Input (English): Question: Every experimental measurement is accompanied by the corresponding experimental error. Experimental errors are classified as systematic and random. On these last ones it is possible to be affirmed that: 
 Options:  <1> They are due to a failure of the experiment or the equipment. <2> They generally cause a positive deviation from the measurement. <3> They are equally likely to be positive or negative. <4> They do not affect the final result because they are random. <5> They affect exclusively the accuracy of the results obtained.
Output (English): 3