The maximum and minimum thermometer reads the

Step 1: Analyze the question The question asks what a Six's maximum and minimum thermometer records.

Step 2: The concept A Six's thermometer has a U-shaped tube with mercury and alcohol. Small steel indices are pushed along by the mercury thread:

• One arm records the highest temperature reached. The index is pushed up by the mercury as the temperature rises and stays at the peak when the temperature falls.
• The other arm records the lowest temperature reached. The index is pushed up as the temperature falls and stays at the lowest point when the temperature rises.

The indices stay in place until you reset them with a magnet. So the thermometer shows the extreme temperatures since the last reset, not "at all times."

Step 3: Eliminate the options

• A and C say "at all times." This is wrong because the readings only cover the period since the last reset.
• B reverses the usual pattern, with the maximum at night and the minimum during the day. Normally the highest temperature occurs during the day and the lowest at night.
• D says the maximum is during the day and the minimum at night, from the last reset. This fits the description.

Step 4: Answer The correct option is D.

Tip: Remember the key phrase "since last reset." The indices only move in one direction, so they hold the extreme values until you reset them with a magnet. Any option saying "at all times" is a trap.