Read the stem literally: it wants the word for shifting from one rung of the socioeconomic ladder to another. That is the definition of social mobility, so match the term to the concept.
Social mobility covers anyone changing position in society, whether they climb up or slide down, and whether the change is within a lifetime or between generations of a family.
The distractors describe different ideas. Social equality is about everyone being on the same level, not moving between levels. Social upliftment is an informal term for helping the poor rise and is not the standard answer. Social insurance is a way of funding healthcare and income support by sharing risk, which has nothing to do with movement between classes.
\[\boxed{\text{Social mobility}}\]