which of the following is valid advice for naming variables?

which of the following is valid advice for naming variables?1. To save typing, make most variable names one or two letters.2. to avoid conflict with names that others are using , use unusual or unpronounceable names.3. TO make names easier to read, separate long words by using underscores or capitalization for each new word.4. to maintain your independence, shun the conventions of your organization.