Concept:Identify the word that is the closest opposite of the underlined word and fits correctly in the sentence gap.
Explanation:The underlined word suggests a lowering or softening of intensity, strictness, or level.
The needed opposite must therefore mean raising or increasing that quality.
"Heightened" means made stronger, more intense, or more strict, so it expresses this opposite meaning.
"Lengthened" and "prolonged" refer only to making something longer in distance or time, not more intense.
"Created" means brought into existence, which does not convey the opposite idea required here.
Thus, "heightened" is the most suitable opposite and fits the sentence context.
Answer:B. heightened