Total revenue:
always increases as price increases.
increases as price increases, as long as demand is elastic.
decreases as price increases, as long as demand is inelastic.
remains unchanged as price increases when demand is unit elastic.

remains unchanged as price increases when demand is unit elastic.

Explanation:

Total revenue = price × quantity

Demand is elastic when a small change in price has a greater effect on the quantity demanded.

If price is increased and demand is elastic, quantity demanded would fall more than the increase in price and total revenue falls.

Demand is inelastic if a small change in price has little or no effect on quantity demanded.

If price is increased and demand is inelastic, change in quantity demanded would be less than changes in price. As a result, total revenue would increase.

Demand is unit elastic if a change in price has an equal proportional effect on quantity demanded. The elasticity of demand always sums up to one.

If price is increased and demand is unit elastic, there would be no change in total revenue.

I hope my answer helps you

d. all of the above are true.