设f₀(x)＝cos x，f₁(x)＝f₀′(x)，f₂(x)＝f₁′(x)，…，f_n₊₁(x)＝f_n′(x)，n∈N^*，则f₂₀₁₁(x)＝

设f₀(x)＝cos x，f₁(x)＝f₀′(x)，f₂(x)＝f₁′(x)，…，f_n_＋₁(x)＝f_n′(x)，n∈N^*，则f₂₀₁₁(x)＝(　　)

A．－sin x B．－cos x

C．sin x D．cos x

设f0(x)＝cos x，f1(x)＝f0′(x)，f2(x)＝f1′(x)，…，fn＋1(x)＝fn′(x)，n∈N*，则f2011(x)＝(　　)

A．－sin x B．－cos x C．sin x D．cos x

设f0(x)＝cos x，f1(x)＝f0′(x)，f2(x)＝f1′(x)，…，fn+1(x)＝fn′(x)，n∈N*，则f2011(x)＝