Lowest level of cognitive achievement is :

Benjamin Bloom's Taxonomy of Educational Objectives divides the cognitive domain into six ordered levels of increasing complexity: Knowledge, Comprehension (Understanding), Application, Analysis, Synthesis, and Evaluation. Each higher level requires the mental processes of every level below it, so mastery must build from the bottom upward.

Among the four levels named in the options, Knowledge is the entry-level skill: it asks only that the learner recall or recognise facts, terms, and basic concepts exactly as presented, with no interpretation, application, or judgment involved. Because every other listed level (Understanding, Application, Evaluation) requires operating on that recalled information in some way, Knowledge is the level with the least cognitive demand.

• Knowledge — recalling facts, terms, or definitions exactly as learned, without interpreting or manipulating them.

• Understanding (Comprehension) — grasping the meaning of information well enough to explain, summarise, or restate it in one's own words.

• Application — using learned rules, concepts, or methods to solve a new problem or handle an unfamiliar situation.

• Evaluation — judging the value, validity, or quality of material or ideas against stated criteria; the most demanding of the four.

Cross-check: the reverse logic confirms this — a learner cannot meaningfully apply, comprehend, or evaluate content they have not first recalled or recognised, but recalling facts requires no prior processing at any of the other three levels. This one-directional dependency confirms Knowledge sits at the base of the hierarchy.