In basic school level science, what is usually taken as the maximum number of fundamental states of matter?

Introduction / Context:
This question checks general science knowledge about the classification of matter into different states. Traditionally, students learn about solids, liquids, and gases. Later, they are introduced to plasma and Bose Einstein condensate, which expands the list. Exams often ask how many states of matter are commonly recognised when these two additional states are included.

Given Data / Assumptions:

• Options include three, four, five, and variable states of matter.
• We consider the states usually mentioned in school and early college level textbooks.
• These include solid, liquid, gas, plasma, and Bose Einstein condensate.

Concept / Approach:
At primary level, only three states are taught: solid, liquid, and gas. As the syllabus advances, plasma is introduced as a high energy ionised state of matter, seen in stars and fluorescent lamps. Bose Einstein condensate is described as a very low temperature state where particles occupy the same quantum state. Together these five are often listed as the main states of matter. Although modern physics discusses many more exotic phases, the question clearly aims at this widely taught set of five states.

Step-by-Step Solution:
Step 1: List the familiar states of matter. Solid, liquid, and gas are the three classical states. Step 2: Add additional states from higher level curriculum. Plasma is introduced as the fourth state of matter. Bose Einstein condensate is introduced as the fifth state of matter. Step 3: Count the total. Total number of such states = 3 + 2 = 5. Hence, the maximum number of states normally recognised in basic teaching is five.

Verification / Alternative Check:
Many exam explanations explicitly say that there are five fundamental states of matter: solid, liquid, gas, plasma, and Bose Einstein condensate. Other phases like quark gluon plasma or superfluid helium are usually treated as advanced topics and not counted when this question appears in general science papers. Therefore, choosing five is consistent with standard exam keys and teaching materials.

Why Other Options Are Wrong:
Option A: Three refers only to solid, liquid, and gas, ignoring plasma and Bose Einstein condensate, which are now commonly taught. Option B: Four includes plasma but still leaves out Bose Einstein condensate, which is often counted as the fifth state in school textbooks. Option D: Variable is not appropriate in this context because the question clearly expects a specific number based on standard curriculum, not on all possible phases known to modern physics.

Common Pitfalls:
Learners may stick with the earliest idea of three states and forget that they later learned about plasma and Bose Einstein condensate. Another confusion arises from popular science articles that mention many exotic states and suggest that the number is not fixed. For exam purposes, it is important to answer according to the level of the syllabus, which treats five states as the commonly accepted maximum.

Final Answer:
The maximum number of states of matter usually recognised at this level is Five.