To form the plural of a noun ending in s, sh, ch, or x, you should add a. es. b. s. c. ies. d. ves.

The correct answer is A. es

Explanation:

In the English language the plural of nouns is usually formed by adding -s to the nouns, for example, the plural of cat is cats, and the plural of house is houses. However, there are cases in which adding only "s" is not correct as the way the plural of nouns is formed also depends on the ending of nouns. In this way according to grammar if the noun ends in sh, s, ch or x such as clash, match, kiss or box, the plural is formed by adding -es, this means the plural forms are clashes, matches, kisses or boxes and this grammatical rule applies to all nouns ending in sh, s, ch or x. Thus,  to form the plural of a noun ending in s, sh, ch or x it is necessary to ad -es.

c) eager anticipation.

the answer is definitely d. sorry for a late response.