在化学诱变剂的作用下，碱基会发生变化，其中亚硝酸具有氧化脱氨的作用，使腺嘌呤变成次黄嘌呤，最终引起（）。

The demand for a product tends to be price inelastic if:（）

A. few good complements for the product are available.

B. few good substitutes for the product are available.

C. people spend a large share of their income on the product.