Select the correct possessive form.
1. hair gel is expensive.
a. jesses'
b. jess's

Option A

Explanation:

The possessive form of any word which is ending with alphabet "s" is not represented the way as it is done for all other words. In case of words that do not end with alphabet "s" , the possessive form is written by putting an apostrophe after the word and then a second "s".

However, the possessive form of words that end with alphabet "s" is represented by simply putting an apostrophe after the word.

In this case, Jesses and Jess are ending with "s" letter, thus their possessive form would be

Jesses'

and

Jess'

Thus, only option A is correct.

its temperature is increasing. this causes molecular vibrations to increase.