Option 1 -> Other variables remain constant - this is the correct definition of ceteris paribus.
Option 2 -> One variable remain constant - incorrect, as it refers to multiple other variables, not just one.
Option 3 -> Other variables remain flexible - incorrect, as this contradicts the meaning of ceteris paribus.
Option 4 -> One variable remain flexible - incorrect, as this doesn't capture the assumption correctly.
Hence, Option 1: Other variables remain constant -> "Ceteris paribus" is a Latin phrase meaning "all other things being equal" or "holding other things constant." This assumption is crucial in economics and research to isolate the effect of one variable on another by keeping all other relevant factors unchanged. For example, when studying how price affects demand, we assume ceteris paribus - that income, preferences, prices of related goods, and other factors remain constant -> correct