Which of the following layers of soil determines its pH value and also its rate of water absorption and retention?

The C-horizon, the weathered parent material below the true soil, largely governs the soil's pH and its water absorption and retention.

The O-horizon is the surface layer of fresh and decaying organic litter, not the pH-setting zone.

The A-horizon is the fertile topsoil rich in humus where roots and life concentrate.

The B-horizon is the subsoil where leached minerals accumulate.

Because the C-horizon is weathered rock, its mineral makeup shapes acidity and moisture behaviour.

Below it lies the unweathered bedrock, sometimes called the R-horizon.