R programming – plot of ml values against range of M values for count data

The questions were these:
questions

The answers i got so far:
answer

need help on c and d please!
Code so far:

The data looks like this:
data output

library(ggplot2)

load("aut2020.RData")

y <- frogs$counts
y
y_bar <- mean(y)
n <- 365