We're working on a shower that has a bench and using kerdi. We just started the water test and realized that we built the shower bench flat. Question: should we...

A) When we tile, slope the tile so the tile is sloped, even though the bench underneath is flat? Maybe using expoxy grout so it's less likely for water to sneak underneath?

B) Instead of tiling, using a solid slab for the bench (granite / quartz)... maybe using kerdifix connecting the slab to the wall kerdi to keep water from sneaking under?

C) Add a slope to the top of the bench and put more kerdi on top to have the slope underneath the tile and have it waterproofed

Or something else? Really appreciate the help!