A 'Hook' activity is the one which makes use of students' existing knowledge and generate interest. Which of the following would be the BEST "hook" activity for Ms. Saloni to use while introducing the topic of soil profile?

Option 3 : Asking students to separate different layers of soil after digging in a farmland. 

A soil profile is a vertical section of soil. It allows for examining the structure of the soil. A soil profile is divided into layers called horizons. The main soil horizons are A, B, C, and D. Asking students to separate different layers of soil after digging in farmland would be the best "hook" activity for Ms. Saloni to use while introducing the topic of soil profile as:

• The soil profile is nothing but discussing different layers present in the soil.
• The student when taken to the field and allowed to dig the soil first of all they identify that the soil has many layers in it, and it is not soft like upper soil.
• Then when they are instructed to separate the layers of soil into upper soil, gravel, and stones, etc. they develop a complete understanding of various layers of soil.
• The concept remains in the minds of children for a long time as the hook activity done by them is the most appropriate one.

Hence Asking students to separate different layers of soil after digging in farmland would be the best "hook" activity for Ms. Saloni to use while introducing the topic of the soil profile. 

On the other hand asking students to plant a seed, collect soil samples, and show videos doesn't suit as an appropriate hook activity for the topic because here the students can't get an idea about the different layers of soil.