Is it true that the precambrian is the largest eon?

yes

Explanation:

"The Precambrian is the largest span of time in Earth's history before the current Phanerozoic Eon (the largest division of geologic time, comprising two or more eras) and is a supereon divided into several eons of the geologic time scale."

Yes, the Precambrian is the largest geological time because it contains 3 eons: Hadean (4,600 - 4,000 MYA), Archean (4,000 - 2,500 MYA) and the Proterozoic (2,500 - 541 MYA). The 3 eons contain eras and many geological periods.

MYA is short for million years ago.

c. businesses/firms & government

d is the right answer