To solve this question, the user needs to know about verb tense.

Now, let's go through each option and explain why it is right or wrong:

A. counted: This option is incorrect because it is in the past tense. The sentence requires present tense verb.

B. counting: This is the correct answer. It is in the present participle form of the verb and is correctly used to form the present continuous tense.

C. count: This option is incorrect because it is an infinitive form of the verb. It doesn't convey the sense of the sentence.

D. counts: This option is incorrect because it is in the third person singular form of the verb and doesn't convey the sense of the sentence.

The Answer is: B