Two Radioactive Nuclides X and Y Both Decay to Stable

Two radioactive nuclides X and Y both decay to stable products.The half-life of X is about a day,while that of Y is about a week.Suppose a radioactive sample consists of a mixture of these two nuclides.If the mixture is such that the activities arising from X and Y are initially equal,then a few days later the activity of the sample will be due

A) predominantly to nuclide Y.
B) predominantly to nuclide X.
C) entirely to nuclide Y.
D) to nuclides X and Y equally.