Among the four normal distributions with probability density

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Among the four normal distributions with probability density functions as shown below, which one has the lowest variance?

1. I
2. II
3. III
4. IV

Correct Option: D

We have Probability distribution function of Normal Distribution

Variance = σ ² is lowest
⇒ σ also lowest
⇒ If σ decreases ⇒ f(x) increases(∵ from (1))
⇒ Curve will have highest peak