You find a sedimentary rock that contains pieces of igneous rock. what is the best explanation for how pieces of igneous rock got there?

There are dozens

Explosive materials such as pumices, lapilli and ashes may be blown by volcanoes thousands of kilometers around and fall in a sedimentary basin.
Erratic are all sorts or rocks transported by glaciers and abandoned wherever the lower altitude will stop their front. Rivers also transport materials from one basin to another. So does the wind.
Rocks of continental origin, such as sandstones, conglomerates etc. are all sedimentary rocks and may well contain igneous fragments.

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.