Read the excerpt from "the revolt of mother."

the woman stood for a moment looking after him, then she went out of the barn across a corner of the yard to the house. the house, standing at right angles with the great barn and a long reach of sheds and out-buildings, was infinitesimal compared with them. it was scarcely as commodious for people as the little boxes under the barn eaves were for doves.

which is the correct definition of the word “infinitesimal” based on its usage in the excerpt?
extremely large
extremely close
extremely small
extremely far away