Which one of the following is incorrectly matched ?
| List-I (Term) | List-II (Meaning) |
| (A) Physiological density | Total population/Net cultivated area |
| (B) Agricultural density | Total agricultural population/Net cultivable area |
| (C) Population density | Total population/Total area |
| (D) Marginal worker | Total population/Total working population |

Identify the part of the sentence that contains a grammatical error:
Each of the boys have submitted their assignment on time.
Rearrange the following parts to form a meaningful and grammatically correct sentence:
P. a healthy diet and regular exercise
Q. are important habits
R. that help maintain good physical and mental health
S. especially in today's busy world