Assertion(A) Black body is an ideal body that emits and absorbs radiations of all frequencies.
Reason(R) The frequency of radiation emitted by a body goes from a lower frequency to higher frequency with an increase in temperature.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is not the correct explanation of A
C. A is true but R is false
D. Both A and R are false.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that a black body is an ideal body that emits and absorbs radiations of all frequencies.
- A black body is defined as an object that perfectly absorbs all incident radiation and also emits radiation at all frequencies when it is at a given temperature.

2. **Understanding the Reason**: The reason states that the frequency of radiation emitted by a body increases from a lower frequency to a higher frequency with an increase in temperature.
- This is based on the principle that as the temperature of an object increases, the energy of the emitted radiation also increases, leading to higher frequencies of radiation being emitted.

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