Concept:
Abnormal changes in white blood cell count are described using specific medical terms.
• Leucocytosis = increase in WBC count
• Leucocytopenia (Leukopenia) = decrease in WBC count
Step 1: Analyze Statement I.
Statement I says:
“Slight increase in WBC count is known as leucocytopenia.”
This is incorrect.
Leucocytopenia means a decrease in WBC count.
Hence Statement I is false.
Step 2: Analyze Statement II.
Statement II says:
“Fall in WBC count is called leucocytosis.”
This is also incorrect.
Leucocytosis refers to an increase in WBC count.
Hence Statement II is false.
Step 3: Final conclusion.
Both statements are false.
\[
\boxed{\text{Both statements are false}}
\]
Therefore option (B) is correct.