Geologists often cannot directly date a rock layer, but instead have to "bracket" its age by finding the ages of nearby rocks and applying relative dating principles to determine the minimum and maximum ages of the rock layer in question. The diagram below shows a conglomerate layer (A) than can't be dated directly; also present are a lava flow (B) and a dike (C). Lava flow B has been dated at 1.3 billion years old and it is known that dike C contains 75% of the Potassium-40 (parent) atoms (the half-life is 1.3 billion years). What is the minimum age of the conglomerate