What components from salary can be shown to gain tax benifits

Hello, My salary breakdown structure is as follows :- Basic 25,333.58 Internet 1,000.00 Petrol and Driver Allowance 10,000.00 Meal Coupons 2,200.00 Employer PF Contribution 1,800.00 Leave Travel Allowance 5,000.00 Fixed Total 45,333.58 Flexible(Including FBP Components) Component Name Monthly House Rent Allowance 10,133.42 Conveyance Allowance Children Education Allowance Medical Allowance 1,250.00 Performance Based Pay Special Allowance 8,017.00 Flexible Total 19,800.42 CTC (Fixed+Flexible) 65,134.00 I want to gain maximum tax benefits, so , below are my questions :- 1. I do not pay rent, so how much in total will I have to invest in ELSS to maximize 80C gains. What should I give to employer as proof of ELSS? 2. Can I show petrol bill in 80C? , I bought car in October, but do not have driver, but in salary, petrol allowance is included. 3. Can I show postpaid mobile bills in 80C? 4. Can I show medical bills of myself, mother and father in 80D? I donot have any mediclaim, neither do my parents? - thanks,