The code is required to produce the output:

Please input a first string : This is the Exam for INF$15112022$

What letter are we counting : e

The count is : $2$

Which code can be used?

a$.$

s$=$input$(\text{'}$Please input a first string : $\text{'})$

l$=$input$(\text{'}$What letter are we counting : $\text{'})$

t$=$s$.$count$($l$.$lower$(),0,$ length$)+$ s$.$count$($l$.$upper$(),0,$ length$)$

print$(\text{'}$The count is : $\%$d$\text{'}\%($t$))$

b$.$

s$=$input$(\text{'}$Please input a first string : $\text{'})$

l$=$input$(\text{'}$What letter are we counting : $\text{'})$

t$=$s$.$count$($l$.$lower, $0,$ len$($s$))+$ s$.$count$($l$.$upper, $0,$ len$($s$))$

print$(\text{'}$The count is : $\%$d$\text{'}\%($t$))$

c$.$

s$=$input$(\text{'}$Please input a first string : $\text{'})$

l$=$input$(\text{'}$What letter are we counting : $\text{'})$

t$=$s$.$count$($l$,0,$ len$($s$))$

print$(\text{'}$The count is : $\%$d$\text{'}\%($t$))$

d$.$

s$=$input$(\text{'}$Please input a first string : $\text{'})$

l$=$input$(\text{'}$What letter are we counting : $\text{'})$

t$=$s$.$count$($l$.$lower$(),0,$ len$($s$))+$ s$.$count$($l$.$upper$(),0,$ len$($s$))$

print$(\text{'}$The count is : $\%$d$\text{'}\%($t$))$