Assertion (A) Rapidly changing temperatures can be measured by thermocouples.Reason (R) The thermal capacity of the junction of a thermocouple is very small.

• Correct answer
  A

  Both $(A)$ and $(R)$ are true and $(R)$ is not 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

  $(A)$ is false but $(R)$ is true

Hence, the correct answer is option: 'A'.