Logical ReasoningDifficulty: Easy

PT114 S4 Q22 Explanation

In humans, ingested protein is broken

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsNecessary Assumption

Keep going in LSAT Lab

  • Save & drill this skill — build targeted practice sets from questions like this one

  • Video walkthroughs — watch every question solved step by step

  • 81 official LSATs — as questions, timed sections & full-length tests

Start practicing free

Free to start

Full official LSAT questions are available through LawHub. This page provides LSAT Lab's explanation, strategy, and review tools without republishing the full official question.

Stimulus

In humans, ingested protein is broken down into amino acids, all of which must compete to enter the brain. Subsequent ingestion of sugars leads to the production of insulin, a hormone that breaks down the sugars and also rids the bloodstream of residual amino acids, except for tryptophan. Tryptophan then slips into a major role in mood elevation, helping one to feel relaxed and anxiety-free.

What this question is testing

Necessary Assumption

Your task

Find the assumption the argument requires in order for its conclusion to hold.

Common trap

Answers that would help the argument but aren't strictly required (sufficient, not necessary).

Winning move

Negate each choice — the right one breaks the argument when negated.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
22.

Which one of the following is an assumption on which the

Answer choices

  1. Trap9% picked this

    Elevation of mood and freedom from anxiety require increasing the level of serotonin

  2. Trap4% picked this

    Failure to consume foods rich in sugars results in anxiety and a

  3. Trap2% picked this

    Serotonin can be produced naturally only if tryptophan is present in

  4. Correct83% picked this

    Increasing the level of serotonin in the brain promotes relaxation and

    Why this is right

    Answer D is correct.

    Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

  5. Trap1% picked this

    The consumption of protein-rich foods results in anxiety and a lowering

Continue the review in LSAT Lab

Save this question, watch the video walkthrough, and drill similar questions in your LSAT Lab account.

Save and practice this skill
LSAT Lab

Turn this review into a targeted study plan.

Save this question, drill more like it, watch the video walkthrough, and track your progress in your LSAT Lab account.

Start practicing free