Aglycosidic bond is (a) a bond between any two carbohydrate molecules. (b) a bond formed between an anomeric carbon atom and any -or group. (c) a bond between anomeric carbon atoms on two separate monosaccharides. (d) any bond that can be broken by reaction with water.

a bond formed between an anomeric carbon atom and any -OR group.

Explanation:

A glycosidic bond is formed between two carbohydrate molecules.

It may also be formed between a carbohydrate and a non carbohydrate molecule as well. However it is observed that the bond is formed between an anomeric carbon of one carbohydrate molecule and any OR group.

so the true statement is:

a bond formed between an anomeric carbon atom and any -OR group.

The other statements are not true as:

(C) a bond between anomeric carbon atoms on two separate monosaccharides: It can be with other non monosaccharide as well.

(D) any bond that can be broken by reaction with water: there are many other bonds which are not glycosidic and can be broken by reaction with water. Example ester linkage.

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.