how did otto i gain support from many church bishops?\n○ by choosing a pope who supported him\n○ by…

Brief Explanations:

Lay investiture is the act of a secular ruler granting ecclesiastical titles and authority. Otto I used this power to appoint bishops, which gave him influence over the Church hierarchy and thus gained the support of many Church bishops. Choosing a Pope (the papal election process was more complex and not solely within Otto I's direct choosing in this context), conquering land (while it gave him secular power, it's not the direct mechanism for bishop support here), and simony (selling Church positions, which was generally condemned and not a legitimate way Otto I would have gained support) are less relevant.

Answer:

by using the power of lay investiture