Explanation
$$ \textbf {Step1: Draw a relevant figure.}$$
At 9 O'clock the minute hand will be at 12 and the hour hand will be at 9 as shown in figure.
$$ \textbf {Step 2: Identify the angles.}$$
From the above figure, we can say that the angle between hour hand and minute hand of the clock is 90,270.
$$ \textbf {Hence, option B is correct.}$$
As ∠ABC and ∠CBA both represent the same angle formed at point B.
Hence, the measures of the ∠ABC and ∠CBA are the same.
$$ \textbf{Therefore, the given statement is true.}$$
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