How many trophic levels are there in the following food chain? Grass - Grasshopper - Frog - Snake

Four

Fun Fact - Locusts are actually species of short-horned grasshoppers, they often gather in large swarms and can destroy entire fields of crops, because a single grasshopper can eat half its body weight in plants per day.

it also supports my hypothesis. if you rest first you can squeeze the clothespin more times. from the data i collected the average of the eight people concluded exercise makes your muscles more fatigued and less able to squeeze the clothespin compared to resting before squeezing.