In the given question, the correct participle to complete the statement would be "visto." Here's the breakdown of why:
1. The sentence is in the present perfect tense, indicated by the use of "han" which is the auxiliary verb for the present perfect tense in Spanish.
2. When forming the present perfect tense in Spanish, you need to use the past participle of the main verb. In this case, the main verb is "ver" (to see).
3. The past participle of "ver" is "visto," which agrees with the auxiliary verb "han" and completes the sentence correctly.
Therefore, the correct choice to complete the statement is "Muchos lo han visto."
