How to access parameter of a method (declared in the method itself) from another method?

I want to access the string parameter declared in a method from another method.
i.e., I made a string parameter called string survey in SaveLocal method. Now I want this to be accessed by the SendEmail method so I can get the string survey as the mail body (mail.Body).

void SaveLocal(string survey, int id)
//save to disk
string fileName = “results” + id.ToString(“D4”);
print("Filename: " + fileName);

    string filePath = Application.persistentDataPath + "/"+fileName + ".json";
    //string path = Application.persistentDataPath;


    byte[] JsonStringBytes = Encoding.UTF8.GetBytes(survey);
    File.WriteAllBytes(filePath, JsonStringBytes);

    InfoText.text += "

" + MainMenuBehaviour.CurrentDictionary.GetKeyValue(“saved_locally”, false);


//code 2

public void SendEmail() { MailMessage mail = new MailMessage();

mail.From = new MailAddress(“”);
mail.Subject = “Test Mail”;
mail.Body = “This is for testing SMTP mail from GMAIL”; //MAIL BODY

SmtpClient smtpServer = new SmtpClient(“”);
smtpServer.Port = 587;
smtpServer.Credentials = new System.Net.NetworkCredential(“”, “senderpassword”) as ICredentialsByHost;
smtpServer.EnableSsl = true;
ServicePointManager.ServerCertificateValidationCallback =
delegate (object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{ return true; };

you cant, just declare it outside. declare the variable outside the method and just assign it inside, local vars memory get errased even if you could access method variables