I (1)/ am having (2)/ three children. (3)/ No error (4)

Answer

2

Explanation

have will replace am having because -
have is a stative verb that usually relates to thoughts, emotions, relationships, senses, states of being and measurements. These Verb sare not used in Contin- uous Tenses.
Simple Tenses are used for them.
Look at the examples given below:
She has a Mercedes. (She owns It.)
She is having lunch. (Sheis eating)
Some stative Verbs are : agree, appear, seem, be, feel, see, etc.