Concept:
To determine grammatical correctness, we check sentence structure, comparative forms, prepositions, and idiomatic usage.
Step 1: Examine sentence A.
\[
\text{Nisha is more funnier than Natasha.}
\]
This sentence uses double comparison:
\[
\text{more + funnier}
\]
which is incorrect.
Correct form:
\[
\text{Nisha is funnier than Natasha.}
\]
Hence, A is incorrect.
Step 2: Examine sentence B.
\[
\text{Rakesh didn't know my address.}
\]
This sentence is grammatically correct.
Hence, B is correct.
Step 3: Examine sentence C.
\[
\text{All the candidates will give a test on Friday.}
\]
The correct expression is:
\[
\text{take a test}
\]
not “give a test” in this context.
Hence, C is incorrect.
Step 4: Examine sentence D.
\[
\text{She scoffed at the idea of revolution.}
\]
The verb “scoffed” correctly takes the preposition “at.”
Hence, D is correct.
Step 5: Examine sentence E.
\[
\text{Beside being a poet, he is also a famous singer.}
\]
The correct word should be:
\[
\text{Besides}
\]
Hence, E is incorrect.
Step 6: Identify the correct sentences.
Correct sentences are:
\[
B \text{ and } D
\]
Step 7: Conclusion.
Thus, the correct answer is:
\[
\boxed{\text{B and D Only}}
\]