With which of the following statements would the author be least likely to agree a. Children naturally and easily learn mathematics. b. Children learn to add before they learn to subtract. c. Most people follow the same pattern of mathematical development. d. Mathematical development is subtle and gradual.

在工业生产中盐酸被广泛应用的原因是（）。

A.清洗能力强

B.无毒害

C.效率低