A taxpayer uses a car to conduct his business. Which of the following statements correct?

a$.$ The taxpayer can claim $12\%$ of the original cost as a deduction as long as the kilometres travelled are less than $5000km.$

b$.$ The taxpayer must keep a log b$$ok irrespective of what method for claiming deductions is used.

c$.$

The taxpayer can claim for one third of expenses for any annual distance incurred, as long as a detailed log$-$book is kept.

d$.$ The taxpayer can claim a deduction for each kilometre travelled, but only up to $5000km.$